• mdadm how to stop a check


    Is a mdadm check on your trusty software RAID array happening at the worst time and slowing down your server or NAS? cat /proc/mdstat Personalities : [raid1] [raid10] md127 : active raid10 sdb4[0] sda4[1] 897500672 blocks super 1.2 2 near-copies [2/2] [UU] [==========>..........] check = 50.4% (452485504/897500672) finish=15500.3min speed=478K/sec ........
  • Linux Debian Ubuntu How To Install PEPPER Faster and Latest Adobe Flash Player in Firefox


    Just run this apt install command sudo apt install pepperflashplugin-nonfree browser-plugin-freshplayer-pepperflash After this restart your browser and check Adobe's site to verify if your Pepper flash is working and showing at least version 32. https://helpx.adobe.com/flash-player.html As you'll see below it will download the latest version which is currently 32 and this was not possible with the old/crappy deprecated adobe-flash plu........
  • mdadm: super0.90 cannot open /dev/sdb1: Device or resource busy mdadm: /dev/sdb1 is not suitable for this array.


    mdadm --create /dev/md0 --level 1 --raid-devices 2 /dev/sdb1 missing --metadata=0.90 mdadm: super0.90 cannot open /dev/sdb1: Device or resource busy mdadm: /dev/sdb1 is not suitable for this array. mdadm: create aborted Sometimes running "partprobe" can fix this. Other times it requires a reboot. One other manual thing that can be done is the following to fix it (if dm is using and blocking it):........
  • using Xvfb on virtual remote ssh server to have X graphical programs work


    Install xvfb apt install xvfb Reading package lists... Done Building dependency tree Reading state information... Done The following additional packages will be installed: libxfont1 libxkbfile1 x11-xkb-utils xauth xfonts-base xfonts-encodings xfonts-utils xserver-common The following NEW packages will be installed: libxfont1 libxkbfil........
  • CentOS 8 how to convert to a bootable mdadm RAID software array


    The cool thing here is that we only need 1 drive to make a RAID 10 or RAID 1 array, we just tell the Linux mdadm utility that the other drive is "missing" and we can then add our original drive to the array after booting into our new RAID array. Step#1 Install tools we need yum -y install mdadm rsync Step #2 Create your partitions on the drive that will be our RAID array Here I assume it is /dev........
  • Ubuntu Linux Mint Debian xorg performance and tear-free tuning for AMD Radeon Based Cards


    I find that the default settings for the radeon driver that is applied to most AMD cards is horrible. For example by default TearFree is not enabled and it causes videos to have some kind of square artifacts. Here are the settings I have found most suitable for AMD cards: You need to create file in the following path and restart Xorg or your computer to apply it: *Beware that making a mistake here will possibly make your computer........
  • Ubuntu Debian Linux Mint r8169 r8168 Network Driver Problem and Solution


    This problem has been around forever, Linux seems to think it is fine to use the r8169 driver for an r8168 NIC but this often causes problems including the link not working at all. In my case ethttool shows the link up and detected but it simply does not work especially on a laptop that has been resumed from suspension. Sometimes it takes several minutes for it to work or to unplug and replug the ethernet. Here is the solution: Install th........
  • Debian Ubuntu and Linux Mint Broken Kernel After Date - New Extra Module Naming Convention


    This is something I've seen some run into. Take an old install of Linux Mint 18.1 ii linux-image-4.4.0-53-generic 4.4.0-53.74 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP i........
  • mdadm force resync when resync=PENDING solution


    cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] md127 : active (auto-read-only) raid10 sdc1[0] sdb1[2] 1953382400 blocks super 1.2 512K chunks 2 far-copies [2/1] [U_] resync=PENDING bitmap: 15/15 pages [60KB], 65536KB chunk Solution force repai........
  • mdadm: add new device failed for /dev/sdb4 as 3: Invalid argument solution


    mdadm --manage /dev/md125 -a /dev/sdb4 mdadm: add new device failed for /dev/sdb4 as 3: Invalid argument Dec 19 01:23:48 storageboxtest kernel: [ 2328.854491] md: sdb4 does not have a valid v1.2 superblock, not importing! Dec 19 01:23:48 storageboxtest kernel: [ 2328.854499] md: md_import_device returned -22 #zero the superblock and try again! mdadm --zero-superblock /dev/sdb4 mdadm --ma........
  • Linux Permissions and Groups Real Usecase for Group Access


    Ihave a directory structure which the primary user needs full access on but wanted a user to access only a specific directory within the main directory (so they could write in there only and nowhere else). Here's what Idid: [root@compevo8001 dllnow]# ls -alh drwxrwxr-x 2 someuser software 4.0K Oct 19 2017 ExpireYMD-2017-11-20 drwxrwxr-x 2 someuser software 4.0K Nov 19 2017 ExpireYMD-20........
  • hwloc-nox set CPU affinity in Linux


    sudo apt-get install hwloc-nox Reading package lists... Done Building dependency tree Reading state information... Done The following NEW packages will be installed: hwloc-nox 0 upgraded, 1 newly installed, 0 to remove and 530 not upgraded. Need to get 151 kB of archives. After this operation, 453 kB of additional disk space will be used. Get:1 http://archive.ubuntu.com/ubunt........
  • Debian Mint Ubuntu compiling xmr-stak


    sudo apt-get install libcurl4-openssl-dev git build-essential autotools-dev autoconf libcurl3 sudo apt-get install libcurl4-gnutls-dev git clone https://github.com/wolf9466/cpuminer-multi sudo apt-get install cmake libpthread-* libmicrohttpd-dev libssl-dev libhwloc-dev git clone https://github.com/fireice-uk/xmr-stak-cpu.git make install cd bin chmod +x xmr-stak-cpu ./xmr-stak -O xmr........
  • wodim / cdrecord error cannot burn DVD or BDR .iso Errno: 5 (Input/output error), write_g1 scsi sendcmd: no error


    dvd+rw-mediainfo /dev/sr0 INQUIRY: [ASUS ][BW-16D1HT ][3.00] GET [CURRENT] CONFIGURATION: Mounted Media: 11h, DVD-R Sequential Media ID: RITEKF1&n........
  • linux mint image convert menu option missing solution


    Ialready have the caja-image-converter option installed but it shows nothing. Weirdly enough if you install nemo and nautilus converter it does show and work inside caja: The solution is to install *-image-converter sudo apt-get install *-image-converter Reading package lists... Done Building dependency tree Reading state information... Done Note, selecting 'n........
  • Linux Mint Black Screen after boot no graphics solution


    This is not the normal "black screen"issue and I was shocked to eventually find out why. The normal advice of reconfiguring Xorg didn't work. Even booting into "Recovery Mode" did not help. Here is the short end of the stick that fixed it: sudo apt-get install mdm mate-desktop-environment Yes you got it right, mdm and the mate-desktop-environment / gnome were somehow uninstalled. This must be whe........
  • mdadm how to stop or start a check


    It's fairly simple to start or stop a check but I do wish mdadm's command had this built in. Sometimes it will do a check at the worst time causing the server to crawl to a halt. Stop check on md126: echo idle > /sys/block/md126/md/sync_action Start check on md126: echo check > /sys/block/md126/md/sync_action ........
  • mdadm how to mount inactive array


    myguy@devbox:~$ sudo mdadm -As myguy@devbox:~$ cat /proc/mdstat |grep sdf md125 : inactive sdf3[2](S) sudo mdadm --manage /dev/md125 --run mdadm: started /dev/md125 ........
  • How to find and mount mdadm arrays automatically


    A great way if you have a bunch of drives and mdadm connected and are looking for backups/archives and don't know what is where! for md in `cat /proc/mdstat|grep md[0-99]|awk '{print $1}'`; do mkdir /mnt/$md; mount /dev/$md /mnt/$md; done........
  • kdenlive titles/text renders as white screen when using .sh script


    When using the .sh script the rendering doesn't work after an upgrade of related packages to kdenlive. kdenlive (kdenlive:amd64 (4:17.04.1+git201705191233~ubuntu16.04.1)) with affine or composite transitions was fine but is now broken during the time of transition it is just a white screen. The previous version was fine: kdenlive:amd64 (4:17.04.1+git201705191233~ubuntu16.04.1 But now I can't find it or install it:........
  • Migrate Centos 7 from Single HDD to mdadm RAID 10 array:


    Done on Centos 7.3 very important as clearly based on older guides it was a lot easier and more simpler! Hint do not use grub2-install! One huge caveat if you are an oldschool user or sysadmin who has avoided UEFIbooting The normal way will not work here if your Centos was using UEFI. Newer systems use it by default. The easiest way to check is to do an fdisk -l if your sy........
  • How to change reserved blocks in Linux partition


    user@box:~$ sudo tune2fs -l /dev/md99 [sudo] password for user: tune2fs 1.42.9 (4-Feb-2014) Filesystem volume name: Last mounted on: /mnt/md50 Filesystem UUID: 976a8655-2619-4587-878c-dab07f7b7652 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Fi........
  • Track 01: 34 of 1726 MB written (fifo 100%) [buf 99%] 3.6x.Errno: 5 (Input/output error), write_g1 scsi sendcmd: cmd timeout after 1.897 (40) s CDB: 2A 00 00 00 44 A9 00 00 1F 00 resid: 6144 cmd finished after 1.897s timeout 40s write track da


    These errors believe it or not are simply because of not being the root user or running with sudo! However if you didn't know to try as root you'd think there was a problem with your burner or disc Essentially it looks like without root you cannot send the required scsi commands to continue writing. Ithink cdrecord should have built-in tests or safeguards to see if it has the permissions to run the required commands. I guess for more advanced users the idea is simila........
  • What happens when you unplug 1 or more devices from an mdadm RAID array to simulate a failure in Linux Ubuntu/Centos/Debian?


    In short the two drives in the array were /dev/sdd and /dev/sde. The kernel sees they were unplugged and have gone down as you can see below. mdadm caught the first one being unplugged /dev/sde and disabled the missing drive. However when the final drive that was part of the array is unplugged it didn't notice at all. Instead it complains about an IO error later for drives that the kernel knows do not exist anymore. [45817.162728] ata4: exception........
  • Migrating from Linux Mint 17.2 mdadm RAID array to a new one (because I upgraded to larger drives).


    1.) Replicate the number of partitions in your new drives. gdisk /dev/sda gdisk /dev/sdb I created 3 partitions of the same same size. partition #1: +1G (/boot) partition #2: +60G (swap) partition #3: rest of it (/) #note if you are using GPT/gdisk you need to create separate a partition at least 1MB in size (in my case I would a 4th partition and mark it type ef02).........
  • mdadm: CREATE group disk not found Incrementally started RAID arrays. Incrementally starting RAID arrays...


    mdadm won't boot in Ubuntu/Mint/Debian anymore. You just get the following in a loop: mdadm: CREATE group disk not found Incrementally started RAID arrays. Incrementally starting RAID arrays... mdadm: CREATE group disk not found Incrementally started RAID arrays. Incrementally starting RAID arrays... mdadm: CREATE group disk not found Incrementally started RAID arrays. Incrementally starting RAID arrays... mdadm: CREATE group dis........
  • mdadm how to recover from failed drive


    Remove the failed partition /dev/sde1 mdadm --manage /dev/md99 -r /dev/sde1 mdadm: hot removed /dev/sde1 from /dev/md99 Now add another drive back to replace it: # mdadm --manage /dev/md99 -a /dev/sdf1 mdadm: added /dev/sdf1 A "cat /proc/mdstat" should show it resyncing if all is well.........
  • mdadm and lvm how to completely disable and remove vg/pv/lv


    In short the solution is just to use vgremove for the actual /dev/mapper device: vgremove /dev/mapper/backups-backuplv box mnt # mdadm --manage /dev/md8 --stop mdadm: Cannot get exclusive access to /dev/md8:Perhaps a running process, mounted filesystem or active volume group? box mnt # lv lvchange lvconvert lvcreate l........
  • mdadm frozen and doesn't realize array is dead/missing failed due to unplugged drives


    This was a surprising bug but I unplugged all drives for an array md127. At first it was just 1 drive and mdadm seemed to notice this. I unplugged the second drive taking the array offline but mdadm did not realize it was offline and still showed a non-existent disk as being part of it. This created problems trying to unmount it or even to stop this array with mdadm freezing. As for how to fix it I can only think of making sure you are not in a mounted path of........
  • mdadm how to make inactive array active


    This happens when you assemble array it doesn't mean it will be active for many reasons: md20 : inactive sdf1[2](S) 732442488 blocks super 1.2 Solution: sudo mdadm --manage /dev/md20 --run........
  • ADATA SU800 256GB 3D NAND Flash SSD Test & Review


    I keep reading these drives are slower, but they are cheap and still SSDand work very fast for my needs. As you can see the sequential read is 481-491MB/s, if I put them in MDADM RAID10 mode (normal RAID1) they should give me well over 900MB/s and with redundancy and being very cheap for what they offer. [1232206.315622] scsi 8:0:1:0: Direct-Access ATA ADATA SU800&........
  • mdadm kernel panic if trying to change --layout on a RAID10


    It is already known this is not possible mdadm --create /dev/md3 --level 10 --layout=f2 --raid-devices=2 /dev/sdc1 /dev/sdd1 mdadm: /dev/sdc1 appears to be part of a raid array: level=raid10 devices=2 ctime=Sat Dec 24 18:44:29 2016 mdadm: /dev/sdd1 appears to be part of a raid array: level=raid10 devices=2 ctime=Sat Dec 24 18:44:29 2016 Continue creating ar........
  • mdadm mirrored RAID1 performance using RAID10 -f2 (Far Layout) is the solution


    The only way I've found in mdadm to make 2 drives perform like a proper RAID 1 (eg. the read speed should be 2x that of a single drive) is to use the --layout=f2 (far 2). mdadm raid10 performance issues. Be very aware that mdadm seems to default to layout=n2 (which means near). In this scenario it means it is like mdadm RAID 1 performance (you get maximum read speeds of a single drive). dd if=/dev/md126 of=/dev/null bs=1M cou........
  • mdadm change wrong device name md127 fix and solution in Linux


    md127 issue, it should be /dev/md3 per mdadm.conf Any time something is mounted as md127 it almost always means there is no entry for this mdadm array in the mdadm.conf in initramfs (which is separate from your actual /etc/mdadm.conf). cat /etc/mdadm.conf ARRAY /dev/md3 metadata=1.2 UUID=b6722845:381cc94e:7a2c5b5f:8e3b7c4f The reason for this is something strange, most Linux OS's bizarrely always keep their own copy of /etc/mdadm.con........
  • How to completely remove mdadm array


    First you have to stop it. mdadm --stop /dev/md0 Then you can remove it: mdadm --remove /dev/md0........
  • mdadm zero-superblock to solve md device created on root device


    It is possible to tell mdadm to create an md device on a raw disk even though it will give you an error, it writes a superblock and this corrupts the partition table which can result in your system not booting. To fix it just zero the super-block on the offending device that you made the mistake in. Eg: /dev/sda mdadm --zero-superblock /dev/sda It is also a way of starting fresh if you wanted to create a new array.........
  • Linux Mint 17 How to Enable File Sharing Option in File Manager


    I still cannot understand how this would not be enabled by default and I struggled to find the reason why with manually installing samba etc.. wondering why the option for sharing was not in the menu. On Linux Mint "MATE" the package is called "caja-share" and on Cinnamon it is called "nemo-share" so edit the below command as necessary: *Also note that the "samba" package is necessary as it is not inst........
  • blocked for more than 120 seconds issues with iowait and timeout on Live Linux distribution while writing to physical disk


    This happened while an mdadm array was syncing, all access from writing a new blank file to opening a small .txt file was very slow: [222117.312078] kjournald starting. Commit interval 5 seconds [222117.685060] EXT3-fs (md0): using internal journal [222117.685096] EXT3-fs (md0): mounted filesystem with ordered data mode [222122.376847] kjournald starting. Commit interval 5 seconds [222122.602825] EXT3-fs (md2): using internal jour........
  • mdadm how to create mdadm.conf config file


    It is as simple as the command below, it will then update your mdadm.conf or create it in /etc/mdadm.conf mdadm --detail --brief --scan > /etc/mdadm.conf ........
  • bash script Get Model and Serial Number of All Hard Disks in Server on Linux


    for disk in `fdisk -l|grep "Disk /dev"|awk '{print $2}'|sed s/://g`; do echo "$disk" && smartctl -d ata -a "$disk" -T permissive|grep -iE 'Device Model:|Serial Number:' echo "---------------" done *Make sure you have smartctl from smartmon tools installed Sample output: /dev/sdc Device Model: ........
  • Windows showing wrong drive size after resizing the VPS/image or cloning howto fix


    1, Enter the command prompt Start -> cmd 2. Start diskpart diskpart 3. Find the drive that has the wrong size list volume 4. Select the volume (in this example we use volume 2) select volume 2 5. Extend the volume extend filesystem *Note the "exten........
  • mdadm real example of recovery and rebuilding of the array on Centos 6


    In this example we have 2 drives in a RAID array and /dev/sdb is the one that failed. /dev/sda1 is also the /boot partition which we tell grub to install on /dev/sdb eg install root (hd0,0) /dev/sda1 on the new drive /dev/sdb (hd1) First copy the partition table from /dev/sda to /dev/sdb dd if=/dev/sda of=/dev/sdb bs=512 count=1 Run partprobe to detect the new partition table partprobe........
  • Centos 6 how to guide convert LVM non-RAID into mdadm 1/10 RAID array live without reinstalling


    Here is the scenario you or a client have a remote machine that was installed as a standard/default minimal Centos 6.x machine on a single disk with LVM for whatever reason. Often many people do not know how to install it to a RAID array so it is common to have this problem and why reinstall if you don't need to? In some cases on a remote system you can't easily reinstall without physical or KVM access. So in this case you add a second physical or disk or already ha........
  • How To Install Linux Mint 17.2 on mdadm RAID with a separate boot partition


    Iwas surprised to see that Linux Mint at the latest 17.2 version still has NO mdadm installer option, and worse the installer will not be able to create a proper booting environment even when you do install it. How to setup mdadm in Linux mint LiveCD sudo su apt-get install mdadm # partition as you need and then create your mdadm devices # create your SWAP md0 mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /d........
  • grub cannot install or boot from mdadm RAID 10 array


    root (hd2,1) Filesystem type unknown, partition type 0x83 grub> root (hd2,2) root (hd2,2) Filesystem type is ext2fs, partition type 0x83 grub> setup (hd2) setup (hd2) Checking if "/boot/grub/stage1" exists... no Checking if "/grub/stage1" exists... no #weird thing about grub is that the drive you enter is considered hd0 For example when booted fu........
  • mdadm create raid10 array with only 2 drives


    mdadm --create /dev/md1 --level 10 --raid-devices=2 /dev/sdb2 /dev/sdc2 --layout=f2 --metadata=0.90 Note that layout=f2 or layout=n2 is very important as without it you'll get a complaint like this: mdadm --create /dev/md0 --level 10 --raid-devices /dev/sdb1 /dev/sdc1 missing missing mdadm: invalid number of raid devices: /dev/sdb1 It is basically more like a prop........
  • How to install grub on virtio KVM with Linux


    I messed up the bootloader by accident on a standard Centos 6.3 install because I turned the /dev/vda1 boot partition into an mdadm raid 1. This was all done correctly aside from one point Ididn't realize was an issue metadata=00.90 is the only thing that will allow you to boot (otherwise grub won't work and you won't boot). So the next step is rescue mode from a CD right? The problem you will find is that grub does not detect your hard drives, this is Ibelieve is be........
  • drbd 8.3 hard drive failure recovery example


    drbd 8.3 hard drive failure recovery drbdadm attach r0 DRBD module version: 8.3.10 userland version: 8.3.8 you should upgrade your drbd tools! 0: Failure: (119) No valid meta-data signature found. ==> Use 'drbdadm create-md res' to initialize meta-data area. ........
  • drbd won't create device if previous partition is on it Command 'drbdmeta 0 v08 /dev/md160 internal create-md' terminated with exit code 40


    This is what fixed it: [root@box13 ~]# dd if=/dev/zero of=/dev/md160 bs=512 count=500 Basically you need to wipe out more than just the 512 byte partition table so 512 bytes * 500 is more than enough to make DRBD happy and think the partition is now empty. The reason this happens is because it gets confused when there is a previous partition with data on the device you are using. root@box13 ~]# d........
  • What a hdd hard drive and mdadm RAID array failure looks like in Linux


    [3805108.257042] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB) [3805108.257052] sd 0:0:0:0: [sda] Write Protect is off [3805108.257054] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [3805108.257066] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [3805108.257083] sd 0:0:0:0: [sda] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB) [3805108.257090] sd 0:0:0:0: [sda] Write Protect is off........
  • mdadm: Cannot open /dev/sda1: Device or resource busy


    This was caused by some weird dmraid setup which kind of takes control of drives even if they're blank/unused. 1. Check the table. dmsetup table ddf1_44656c6c202020201000006010281f0b3f5195b77cf86172: 0 3905945600 linear 8:0 0 ddf1_44656c6c202020201000006010281f0b3f5195b77cf86172p3: 0 37124096 linear 253:0 284547072 ddf1_44656c6c202020201000006010281f0b3f5195b77cf86172p2: 0 283496448 linear 253:0 1050624 ddf1_44656c6c2020202010........
  • mdadm how to add additional RAID 1 drives


    This is a great way to upgrade your RAID array or move it/copy it to a new set of hard drives. Eg. you have a current RAID 1 array on older/slower drives. Just add at least 1 of the new drives to the array, update grub/install it and then boot into it. Then you have a transparent data migration that is fully synchronized. mdadm --grow /dev/md126 --raid-devices 3 md127 : active raid1 sdc1........
  • mdadm increase recovery sync/resync speed slow solution/fix


    The units in echo are kB as in kilobyte. Setting a high sync speed echo 120000 >/proc/sys/dev/raid/speed_limit_min This will increase the speed, note that sometimes a rebuild is slow due to current disk activity/iowait. If that is not the cause then you may have a hardware issue (controller, cable or a bad drive). Setting a lower sync speed echo 1200 >/proc/sys/dev/raid/speed_limit_max........
  • LSI MegaRAID Adventures, Guide and HowTo


    LSi Megaraid At first it was configured as a RAID 0, then I deleted the Virtual Disk Group. I thought both drives would be shown and detected in Linux as sda and sdb but it actually shows nothing. To make them work you have to hit Ctrl+R before the system boots (when prompted) and create a Virtual Disk Group. In my case I created each one as RAID 0 (with a single drive only) as I just wanted JBOD but there is no such option or default in these Dell Pe........
  • mdadm enable bitmap to speed up rebuilds


    Have you ever unplugged the wrong drive and then had to rebuild the entire array? It may not be a big deal in some ways but it does make your system vulnerable until the rebuild is done. Many distros often enable the "bitmap" feature and this basically keeps track of what parts need to be resynced in the case of a temporary removal of a drive from the array, this way it only needs to sync what has changed. To enable bitmap to speed up rebuilds and sync........
  • mdadm create RAID 1 array example


    mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sda3 /dev/sdb3 cat /proc/mdstat Personalities : [raid1] md2 : active raid1 sdb3[1] sda3[0] 1363020736 blocks super 1.2 [2/2] [UU] [=>...................] resync = 8.3% (113597440/1363020736) finish=276.2min speed=75366K/sec ........
  • SSH Can't Login/Hang


    Client Log OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug1: Connecting to 192.168.1.253 [192.168.1.253] port 22. debug1: Connection established. debug1: permanently_set_uid: 0/0 debug1: identity file /root/.ssh/identity type -1 debug1: identity file /root/.ssh/id_rsa type 1 debug1: identity file /root/.ssh/id_d........
  • mdadm recover from dead drive


    mdadm --manage /dev/md3 --add /dev/sda1 cat /proc/mdstat Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] md0 : inactive sdd2[1] sdd1[2](S) 31270272 blocks md3 : active raid1 sda1[2] sdb1[1] sdc1[3](F) 943730240 blocks [2/1] [_U] [>....................]........
  • kvm cannot boot xen guest using lvm


    This booting error is because the Xen PV guest image uses the Xen kernel, this is not compatible with anything but a host running a Xen kernel. I did a kpartx -av virtual.img and then it created some partitions that showed up in fdisk. I mounted it and did a chroot into it and removed the xen kernel and installed a normal kernel but Xen still shows the same kernel in Grub (only the Xen one). This is strange but it seems like this Xen PV guest has some sort of hidden or........
  • mdadm: /dev/sdb1 not large enough to join array solution


    mdadm --manage /dev/md1 --add /dev/sdb1 mdadm: metadata format 00.90 unknown, ignored. mdadm: metadata format 00.90 unknown, ignored. mdadm: metadata format 00.90 unknown, ignored. mdadm: /dev/sdb1 not large enough to join array md1's first primary member /dev/sda3 has 57394 cylinders while the /dev/sdb1 has 57393 (1 less cylinder) which is why it won't work. fdisk -l /dev/sda3 Disk /dev/sda3: 47........
  • mdadm how to add a device to an array after a failure


    This array is a RAID 1 and in this case 1 of the 2 drives failed (a WD drive and I've found them to be the weakest and most unreliable of any brand and are easily damaged/DOA when shipping them). mdadm --manage /dev/md0 --add /dev/sdb1 The above assumes the array you want to add to is /dev/md0 and the device we are adding is /dev/sdb1 *One thing to remember is to make sure the partition you are adding is the correct size for the array. You can also g........
  • Debian UUID not working


    Neither the blkid or the UUID internal to mdadm work to automount for some reason in Debian partprobe doesn't work but was a good suggestion from: http://pato.dudits.net/2008/11/03/special-device-uuidxxxxxxxxxxxxxxxx-does-not-exist-especially-with-lvm mount: special device /dev/disk/by-uuid/431b9b96-29e8f298-e89bd504-7065bddd does not exist mdadm -D /dev/md_d12 mdadm: metadata format 00.90 unknown, ignored. /dev/md_d12: &nb........
  • mdadm/Debian problem


    This is one in a series of weird things whichIthought was motherboard related (I RMA'd the motherboard), the RAM tests fine with memtest86 and I used badblocks on both RAID 1 members with no errors and smartctl is happy with them. Basically the array crashes the kernel a lot and has issues when writing. [112322.723465] md0: rw=0, want=14958668696, limit=1887460480 [112322.731077] attempt to access beyond end of device [112322.731087] md........
  • How To Test If Your Hard Drive Is Good/Signs of dying hard drive


    I like dd, although it only reads it, usually a read test of the entire disk will uncover if your hard drive is bad in some parts. This is a good thing to do at least once a month, a lot of times bizarre program behavior, laginess and crashing/unnmounting problems etc.. are due to a failing disc and SMART won't know it or indicate a problem: We must also remember there's never a guarantee, I've found that ever since we moved to larger and more platters per drive with 1TB drives........
  • GRUB Solution to error "Error 6: Mismatched or corrupt version of stage1/stage2"


    GNU GRUB version 0.97 (640K lower / 3072K upper memory) [ Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else TAB lists the possible completions of a device/filename.] grub> root (hd1,0) Filesystem type is ext2fs, partition type 0xfd grub> setup........
  • How to recover from dead DRBD partition/hard drive in two simple commands


    This assumes that you've at least created the correct partition for your DRBD already. Notice that I am "diskless", that's because either your DRBD partition doesn't exist/has been renamed (eg. sdb becomes sda when sdb dies and you reboot) or because that drive is really actually dead/gone. *If you need to permanently change the partition/device for your resource be sure to edit /etc/drbd.conf on both hosts and reload the config. (replace r0 with........
  • Are my WDEARS20 Drives dying already?


    This happened during a RAID array check: SMART says both drives pass the test, but I'm doing a long test on them and hopefully this is not a hardware error. Apr 3 04:22:01 remote kernel: md: syncing RAID array md2 Apr 3 04:22:01 remote kernel: md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc. Apr 3 04:22:01 remote kernel: md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reconstruction. Apr........
  • Linux High IOWAIT updatedb can't be killed and crash with mdadm


    high IO wait 424 root 39 19 1900 848 552 D 0.0 0.0 0:00.91 updatedb root 424 0.0 0.0 1900 848 ? DN Mar11 0:00 /usr/bin/updatedb -f sysfs?rootfs?bdev?proc?cpuset?binfmt_misc?debugfs?sockfs?usbfs?pipefs?anon_inodefs?futexfs?tmpfs?inotifyfs?eventp........
  • Enable SPAMASSASSIN on Postfix in 5 minutes


    Centos 5 Postfix and SPAMASSASSIN Tutorial yum install spamassassin chkconfig spamassassin on vi /etc/mail/spamassassin/local.cf ############## #required_hits 5 #report_safe 0 #rewrite_header Subject [SPAM] #5 is the least restrictive (means only the most obvious SPAM is caught. 0 is obviously the most restrictive/sensitive and would have lots of false positives require........
  • CPU #1 not responding - cannot use it.


    I think this will be useful to others because I have a server that kept crashing mysteriously during intense disk usage/RAID checks. It would only crash during the weekly RAID integrity check. ThenI noticed during a reboot that not all CPUs were being brought up, as a result this actually creates much higher temperatures with the output I got from sensors, just booting the system produced higher than normal temperatures. You can imagine that a full blown RAID check........
  • updatedb/mdadm caused a kernel panic?


    Jan 16 04:02:03 centosbox syslogd 1.4.1: restart. Jan 16 04:07:34 centosbox kernel: INFO: task updatedb:20771 blocked for more than 300 seconds. Jan 16 04:07:34 centosbox kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. Jan 16 04:07:34 centosbox kernel: updatedb D F78BE050 6476 20771 20766&n........
  • mdadm Centos 5 automatic resync


    This made me nervous but it's clearly a cronjob based on the messages log that happens every Sunday at about 4:22. I actually can't find any evidence of it in cron.d cron.daily but it is there somewhere obviously. What I don't get is why doesn't this cronjob do a datacheck like Ubuntu's cronscript does? When you unnecessarily rebuild the array you lose your redundancy during that point which makes your data extremely vulnerable. *Update I did a grep of &q........
  • mdadm/md-check how to check array integrity without rebuilding


    This doesn't seem to be widely known (maybe it's in some documentation that none of us read though)but there's an easy way to check the integrity of any mdadm array: sudo echo check > /sys/block/md0/md/sync_action -bash: /sys/block/md0/md/sync_action: Permission denied sudo will never work, this only works as root since echo is not actually a binary/command. It is built-into bash. /sys/devices/virtu........
  • md: data-check of RAID array md3


    This really made me nervous but notice the mdstat says "check". This is because in Ubuntu there is a scheduled mdadm cronscript that runs everyday on Sunday at 00:57 that checks your entire array. This is a good way because it prevents gradual but unnoticed data corruption which Inever thought of. As long as the check completes properly you have peace of mind knowing that your data integretiy is assured and that your hard drives are functioning properly (I'........
  • mdadm: metadata format 00.90 unknown, ignored.


    mdadm: metadata format 00.90 unknown, ignored. This happens with various versions of older mdadm such as mdadm - v2.6.7.1 - 15th October 2008 It is all because an extra 0 in 00.90 in /etc/mdadm/mdadm.conf that it doesn't like (it doesn't seem to cause any problem except that message though): Solution - Edit your /etc/mdadm/mdadm.conf and change 00.90 to 0.90 in your arrays: ARRAY /dev/md3 level=raid1 num-devices=2 metadata=0.90 UUID=f41a4644:6b2a05f........
  • mdadm RAID 1 adventures


    I separated the 2 drives in the RAID 1 array. 1 is the old one /dev/sda and is out of date, while the separated other one /dev/sdc was in another drive and mounted and used with more data (updated). I wonder how mdadm will handle this: usb-storage: device scan complete md: md127 stopped. md: bind md: md127: raid array is not clean -- starting background reconstruction raid1: raid set md127 active with 1 out of 2 m........
  • mdadm won't boot due to fsck error


    Nov 29 20:17:58 ubuntu kernel: [ 1157.180789] md: md1 stopped. Nov 29 20:17:58 ubuntu kernel: [ 1157.180829] md0: unknown partition table filesystem not responding/reading properly with du or rsync (this needed an fsck). [ 2571.489217] EXT3-fs error (device md2): ext3_lookup: deleted inode referenced: 35923106 [ 2571.942299] EXT3-fs error (device md2): ext3_lookup: deleted inode referenced: 35923110 [ 2571.9568........
  • Ubuntu 10.04/GRUB2 mdadm won't boot


    Moving to RAID was a pain. What you have to do is the following from an existing install: Install mdadm Create your mdadm RAID 1 array on your spare hard drive. Start it with the missing disk. rsync the entire contents of your current / to the md partition. Here's a good way of doing it: rsync -Pha --exclude=/proc/* --exclude=/sys/* --exclude=/mnt/* /. /mnt/md2........
  • How to chroot properly into your OS/distro


    From a LiveCD or if you're doing something like converting your non-RAID install to mdadm here's how you would chroot properly (you have to mount your proc, sys and dev on the running system/LiveCD to your chroot environment if you want things to work right, especially if you need to run update-initramfs due to a driver change etc..) *replace "path" with your mount/chroot path mount -o bind /proc /mnt/path/proc mount -o bind /dev/ mnt/pa........
  • Revert to GRUB 0.97/1 instead of GRUB2


    had trouble trying to revert Ubuntu 10.04 LTS from grub2, won't boot mdraid and did not even install mdadm during the installation! I have tried moving back to GRUB 0.97 backed up original /boot and then copied /boot from an old Debian install. Modified device.map and menu.lst and put the appropriate kernels and initrd for Ubuntu back in /boot I ran grub: root (hd0,1) grub> setup (hd0) Checking if "/boot/grub/stage1........
  • mdadm Linux Software RAID QuickStart Guide


    Create New RAID 1 Array: First setup your partitions (make sure they are exactly the same size) In my example I have sda3 and sdb3 which are 500GB in size. mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sda3 /dev/sdb3 mdadm: array /dev/md2 started. Check Status Of The Array *Note I already have other arrays md0 and md1. You can see below that md2 is syn........
  • md: kicking non-fresh sda1 from array! - fix/solution


    md: Autodetecting RAID arrays. md: autorun ... md: considering sdb1 ... md: adding sdb1 ... md: adding sda1 ... md: created md0 md: bind md: bind md: running: md: kicking non-fresh sda1 from array! md: unbind md: export_rdev(sda1) raid1: raid set md0 active with 1 out of 2 mirrors The md0 raid kicked sda1 ou........
  • mdadm when a RAID 1 member dies


    [27969.398749] sd 5:0:0:0: [sdb] 3907029168 512-byte hardware sectors (2000399 MB) [27969.398749] sd 5:0:0:0: [sdb] Write Protect is off [27969.398749] sd 5:0:0:0: [sdb] Mode Sense: 00 3a 00 00 [27969.398749] sd 5:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [27972.117543] ata6.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x0 [27972.117543] ata6.00: irq_stat 0x48000000 [27972.117543] ata6.00: cmd 60/08:00:ff:7........
  • mdadm "auto-read-only" Linux Software RAID solution


    If you have the "(auto-read-only)" beside an arrayI have no idea why that happens but it is easy to fix. Just run "mdadm --readwrite /dev/md1" (rename md0 to the device with the problem and it will begin to resync. md1 : active (auto-read-only) raid1 sdb2[0] sda2[1] 19534976 blocks [2/2] [UU] resync=PENDING ........
  • Use rcconf to edit startup/init.d/init scripts on Debian/Ubuntu based distributions


    I've never understood how to enable and disable services for different run levels in Debian based distros, it's just weird, annoying and doesn't make sense. I much prefer chkconfig from RHEL. Just install the package called 'rcconf' and be done with it. rcconf makes things easy for you. apt-get install rcconf Reading package lists... Done Building dependency tree Reading state information... Done........
  • mdadm: /dev/sda1 is too small: 0K - solution


    I was creating a RAID array and got this error: mdadm: /dev/sda1 is too small: 0K mdadm: create aborted Of course sda1 is not too small, both partitions sda1 and sdb1 are identical in size: Disk /dev/sda: 2000.3 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x00000000 Device Boot Sta........
  • mdadm can you downgrade the superblock?


    Why would you want to downgrade the superblock? Old mdadm verisons like mdadm 2.5.6 only use the 0.90 superblock/metadata and new versions use 1,1.0,1.1 and 1.2 superblocks by default. There are some annoying caveats with this, first of all the new superblocks (later than 0.90) CANNOT be read by GRUB, so you won't even be able to install GRUB. Even worse, old versions of mdadm CANNOT automatically detect arrays even if they were created with a new version of mdadm with th........
  • Why does mdadm have two sets of UUID's?


    Which one does the OS care about? blkid says the UUID is "787f1fa4-b010-4d77-a010-795b42884f56" while md insists its UUID is "4d96dd3b:deb5d555:7adb93cb:ce9182d9" When in doubt, do we assume the OS takes the one from blkid? /dev/md0: UUID="787f1fa4-b010-4d77-a010-795b42884f56" TYPE="ext3" [root@localhost ~]# mdadm -D /dev/md0 /dev/md0: Version : 0.90 &........
  • mdadm force/fix proper md127 name


    I have an md0 arary that my Centos install refers to. I feel this is half the reason why it won't boot anymore. I saw the initrd for Centos was assembling it as md127 even though it was known as md0. The reason for this is because I used mdadm --assemble --scan to detect the array on a LiveCD. I had no idea this name would stick (but now I realize the name is permanently stored in the metadata once you mount md127 or whatever random name assemble gives it). W........
  • Debian 5.04 RAID 1 mdadm boot problem GRUB error


    I successfully created a single RAID 1 partition which includes /boot inside it and my root directory through the Debian installer. It said GRUB installed successfully but when I try booting the OS it seems GRUB can't read anything. When trying to boot from GRUB GRUB Loading stage 1.5. GRUB loading, please wait... Error 2 I get "Error 2" when trying to boot Debian. I also notice from a LiveCD that........
  • Centos 5.5 RAID 1 boot issue


    I installed 5.5 with a 300GB RAID 1 partition (boot is also on this partition). It booted up fine the first few times until after I used a Live CD and accessed the array, and it became named /dev/md127 for some reason. Now whenI boot into CentOS I get a kernel panic and different errors, once I got "invalid superblock", even though the array is fine (it didn't happen again, probably because I was sure to dismount and stop the mdadm array properly). Here's what........
  • chroot into an off-line Linux version using a LiveCD/USB


    It's not just as simple as running the chroot command, you need to ensure the /proc and /dev entries are passed through and populated to the chroot environment. Step 1 - Mount Your Off-lineOS mount /dev/sda1 /mnt Step 2 - Mount Proc mount -t proc none /mnt/proc Step 3 - Mount Dev Most guides will tell you to use this: mount -o bind /dev /mnt//dev but that doesn't work for some reason in many cases: mount: wron........
  • mdadm Linux Software RAID auto-detect and assemble RAID Array


    mdadm --assemble --scan mdadm: /dev/md/diaghost05102010:2 has been started with 2 drives. mdadm: /dev/md/diaghost05102010:1 has been started with 2 drives. mdadm: /dev/md/diaghost05102010:0 has been started with 2 drives. -bash-3.1# cat /proc/mdstat Personalities : [linear] [raid0] [raid1] [raid6] [raid5] [raid4] [multipath] md125 : active raid1 sda1[0] sdb1[1] 14658185 blocks super 1.2........
  • Seagate Drive 500GB Drive Dying


    This drive is clearly on the way out, the Kernel knows it but I'm surprised that SMART is not concerned. I didn't blame Seagate for their past issues until now. This hard drive has hardly been used and has not even been powered on for a year according to SMART. Home page is http://smartmontools.sourceforge.net/ === START OF INFORMATION SECTION === Model Family: Seagate Barracuda 7200.11 Device........
  • Linux AHCI Hotswap Tips - Remember To Reread The Partition Table WITHOUT rebooting


    From the package "parted" you can use the command "partprobe" to re-read the partition table. I really hate rebooting, and that's what Iloved to hear about AHCI motherboards, that they allow hotswap so you don't have to reboot. But that's only as good as the OS, if the OS does not reload the partition table you won't be able to do anything with that new drive you attached without rebooting. Yes, even without re-reading the partiton table Linux will........
  • Convert HDD/Hard Drive Partition(s) into non-RAID into RAID 1 using existing data without data loss and without reformatting.


    Before we start I take no responsibility for this, you should have a backup and if you make a mistake during this process you could wipe out all of your data. So backup somewhere else before starting this as a precaution, or make sure it's data you could afford to lose. The RAID 1 Setup (Hardware Wise) I've already setup my 2 x 1TB (Seagate) drives with identical partitions, make sure your new hard drive (the empty one) is setup like your curr........
  • The New Chips on the Block


    The New Chips on the BlockThe New Chips on the Block By Bruce Gain Story location: http://www.wired.com/news/infostructure/0,1377,67795,00.html 02:00 AM Jun. 13, 2005 PT We have embarked upon a new era in x86 PC computing -- so say chip giants AMD and Intel following their launches of dual-core PC processors. So how will dual-core processing change your PC computing experience? Our FAQ should help you decide whether or when you sho........
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