• Why SMART is not smart at all and doesn't properly predict disk errors that cause a kernel panic or crash


    Before getting into the output here is my typical experience with SMART, there is what I call a "bad disk" with pending and uncorrectable sectors that cannot be reallocated. It has caused a kernel panic and system crash repeatedly as we can see from the logs. But SMART says it has "PASSED" its self assessment. SMART is still useful to me but it is more about looking at Current_Pending_Sector. Any time I have had anything but 0 for that attribute it........
  • migration/4 migration 4 is using too much CPU


    top - 13:02:52 up 603 days, 19:19, 2 users, load average: 5.01, 4.15, 3.44 Tasks: 604 total, 5 running, 599 sleeping, 0 stopped, 0 zombie Cpu(s): 17.7%us, 36.1%sy, 0.0%ni, 42.0%id, 4.1%wa, 0.0%hi, 0.2%si, 0.0%st Mem: 16278908k total, 4269684k used, 12009224k free, 119672k buffers Swap: 8k total, ........
  • Linux How To Free Wasted Memory RAM in Buffers


    We all know Linux is known for good memory management but is it really? It seems all on its own with hardly anything running that you can come back in days or weeks and find that almost all of your RAMis used! And many will say "no don't worry it's buffers for optimization" but it doesn't seem to help because what is in buffers is not available to use for new programs running or ones that allocate more RAM as far as Ican tell. The reason Iknow........
  • vino server error cannot login


    10/07/2018 03:05:14 PM [IPv4] Got connection from client10.10.25.1 10/07/2018 03:05:14 PM other clients: 10/07/2018 03:05:14 PM Client Protocol Version 3.7 10/07/2018 03:05:14 PM Advertising security type 18 10/07/2018 03:05:14 PM Client returned security type 18 10/07/2018 03:05:14 PM TLS Handshake failed: Could not negotiate a supported cipher suite. 10/07/2018 03:05:14 PM Client10.10.25.1 gone 10/07/2018 03:05:14 PM Statistics:........
  • USB 3.0 External HDD Enclosure Seagate UAS problems - [sdd] tag#1 CDB: Write(16) 8a 00 00 00 00 01 70 04 08 68 00 00 00 08 00 00


    This is a 8TB Seagate external USB 3.0 device apparently newer kernels use a module called "UAS" instead of "USB Storage" which causes issues as a lot of devices are not properly supported in UAS mode by the kernel driver. The solution some say is to disable UAS specifically for your USB device but I'd rather just disable UAS altogether. Solution blacklist UAS: *do not do this it does not work and just causes your USB 3.0........
  • 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........
  • Linux shows my drive as being dead is it really? Buffer I/O error on device sdb, logical block 0 sd 3:0:0:0: [sdb] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00


    Normally the below would indicate a failing or failed drive. In this case the SATA port was unplugged and sometimes the Linux kernel/motherboard even with AHCIjust don't play nice and can't handle it. What happened is Iplugged in a new drive after removing another one. However the log shows that after the old drive was plugged in the Linux kernel kept complaining thinking the drive was there but not responding properly. This continued even with reseating........
  • 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........
  • 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........
  • ERROR 2013 (HY000): Lost connection to MySQL server during query


    The solution is simple but strange, if you copy your /var/lib/mysql directory to another server and think it will work, be sure to check if you have /var/log/mysql and binary log files. If you do, the server will not work and will give you errors like below and crash without the proper log files. UPDATE user SET password=password("newpass") WHERE user='root'; flush privileges; ERROR 2013 (HY000): Lost connection to MySQL server durin........
  • OpenVZ Migration Hostnode Containers from Centos 5 to Centos 6


    migrating from an old OpenVZ (Centos 5) to new OpenVZ (Centos 6) Also if migrating from 32-bit HN to 64-bit your RAM will probably be much bigger than it should be! 16x bigger eg. 32bit HN: total used free shared buffers cached Mem:&nb........
  • 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........
  • Centos/obfsproxy errors


    I never did get it working, it is too bad as obfsproxy should really be an option and integrated into the OpenVPN client and server or something similar: yum -y install python-pip python-devel No package python-pip available. #install the EPEL repo python-pip install obfsproxy python-pip install obfsproxy -bash: python-pip: command not found pip install obfsproxy &........
  • Linux Kernel EDAC errors EDAC MC0: UE row 0, channel-a= 0 channel-b= 1 labels "-": NON-FATAL recoverable (Branch=0 DRAM-Bank=0 Buffer ID = 0 RDWR=Read RAS=0 CAS=0 NON-FATAL recoverable Err=0x800 (Non-Aliased Uncorrectable Patrol Data ECC))


    I'm not sure why I'm getting these but all memory modules are the exact same and all passed memtest successfully although they are ECC. I've heard that ECC RAM can't be tested as well and the kernel seems to indicate they are non-fatl recoverable errors. I wonder if the BIOS has aggressive RAM timing or maybe the controller or motherboard is bad. [ 12.716515] EDAC MC: Ver: 2.1.0 [ 12.717771] EDAC MC0: Giving out device to........
  • Openvz OOM Centos Issue Memory Config Settings Solution


    Linux box13. 2.6.32-042stab076.5 #1 SMP Mon Mar 18 20:41:34 MSK 2013 x86_64 x86_64 x86_64 GNU/Linux even setting privvmpages to a specific setting DOES not affect "free -m" in containers. This is probably a kernel issue 23:36:29 up 159 days, 7:12, 4 users, load average: 0.42, 0.44, 0.33 [root@box13 ~]# free -m total&n........
  • WD 20EARX 2TB Bad within days


    This is just trying to read 5GB off the drive with dd and the drive initially tested ok but shortly after I wondered why I was seeing 2MB/s read speeds. Notice the "current_pending_sector", anytime I've seen it at anything above 0 even with no other bad fields/attributes, it means the drive is bad. ata1.00: exception Emask 0x0 SAct 0x3 SErr 0x0 action 0x0 ata1.00: irq_stat 0x40000008 ata1.00: failed command: READ FPDMA QUEUED ata1.00: cmd 60/00:00:........
  • How To Burn ISO Image using cdrtools/dvdrtools for Linux/Unix Ubuntu/Debian/RHEL/Centos etc..


    It really is as simple as: cdrecord -v dev=/dev/sr0 pathtoyourisoimage.iso -v is for verbose, I prefer it but if you don't you won't see as much output like below (I like to know the details and exactly what's happening) dev=/dev/sr0 specifies the device name of your burner (they say not to use it and to specify some weird annoying device string but using the raw /dev has always worked for me and is how it should have been implemented from the start IMHO)........
  • Linux Out of Memory OOM Object Killer Solution "Out of memory: kill process 1955 (sshd) score 81 or a child"


    I had a system running a 128MB live CD image with 2.8 gigs of available RAM and the OOM kernel killer went crazy when using dd for more than 8 minutes and kept killing everything. I've read that this is due to a low-memory issue and paging in the kernel and 32-bit systems with lots of RAM. I even enabled swapspace on my LiveCD and the issue happened 25 minutes into dd rather than 8 minutes, so what gives? Also no swap space was ever used! cat /proc/s........
  • 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........
  • Kernel/make compilation time and how to improve compile times/compile the Linux kernel faster without hardware upgrades


    I thought only a faster CPUand SSDwould help but I already have a Quad-Core CPU and it wasn't being maxed out. The actual tests were performed on an AMD-V enabled 128MB dual core VMWare container though. There is a flag that can be passed to make in order to start multiple threads, by specifying 4 threads I was able to reduce the whole kernel compilation time from scratch by about 50%! (65minutes vs 31minutes!). *Yes I did do a make clean before each co........
  • MySQL NEVER delete ib_logfile0 or ibdata1 or you'll lose data


    don't delete /var/lib/mysql/ib_logfile0 or ibdata1 or mysql won't restart I didn't realize they were internal and not part of replication like the relay files! /usr/libexec/mysqld: ready for connections. Version: '4.1.22-log' socket: '/var/lib/mysql/mysql.sock' port: 3306 Source distribution 110127 16:31:00 [Note] /usr/libexec/mysqld: Normal shutdown 110127 16:31:00 InnoDB: Starting shutdown...........
  • 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........
  • Ubuntu 9.04 Crash


    CPU/Kernel/MB/RAID problem? Jan 5 12:45:05 testbox kernel: [653298.890004] BUG: soft lockup - CPU#0 stuck for 61s! [hal-acl-tool:4168] Jan 5 12:45:05 testbox kernel: [653298.890005] Modules linked in: vmnet vmci vmmon binfmt_misc drbd video output input_polldev ocfs2_stackglue ocfs2_dlmfs ocfs2_dlm ocfs2_nodemanager configfs k8temp hwmon_vid lp snd_hda_intel snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi........
  • Installing Webmin & Enabling SSL


    Webmin Setup Centos 5: wget http://downloads.sourceforge.net/project/webadmin/webmin/1.530/webmin-1.530-1.noarch.rpm?r=http%3A%2F%2Fwww.webmin.com%2Fstandard.html&ts=1294339690&use_mirror=surfnet [1] 24229 [2] 24230 [root@host ~]# --2011-01-06 21:48:20-- http://downloads.sourceforge.net/project/webadmin/webmin/1.530/webmin-1.530-1.noarch.rpm?r=http%3A%2F%2Fwww.webmin.com%2Fstandard.html Resolving downloads.sourceforge.net... 216.34.181.........
  • Buffer I/O error on device fd0, logical block 0


    Virtually no system has a floppy disk drive anymore but you will often find your Linux distribution insists that you do or should have one :) The solution is to remove the floppy module and prevent it from loading on the next reboot. rmmod floppy Centos/RHEL echo "blacklist floppy">> /etc/modprobe.d/blacklist Debian/Ubuntu sudo echo "blackli........
  • connect: No buffer space available Oct 18 12:21:03 vps kernel: printk: 177 messages suppressed. Oct 18 12:21:03 vps kernel: Neighbour table overflow.


    ping test.com connect: No buffer space available /var/log/messages Oct 18 12:21:03 vps kernel: printk: 177 messages suppressed. Oct 18 12:21:03 vps kernel: Neighbour table overflow. Solution in /etc/sysctl.conf: net.ipv4.neigh.default.gc_thresh1 = 4096 net.ipv4.neigh.default.gc_thresh2 = 8192 net.ipv4.neigh.default.gc_thresh3 = 8192 net.ipv4.neigh.default.base_reachab........
  • rsync halted froze Out of memory: kill process 7559 (rsync) score 635 or a child Killed process 7559 (rsync)


    Out of memory: kill process 7559 (rsync) score 635 or a child Killed process 7559 (rsync) I was surprised to see this in my dmesg whenmy rsync backup suddenly stalled/stopped. This system has 3 gigs of RAM and lots of free memory so I don't understand what is happening. rsync invoked oom-killer: gfp_mask=0x200d2, order=0, oomkilladj=0 Pid: 7600, comm: rsync Not tainted 2.6.24.2 #83 [] oom_kill_pr........
  • Compaq V2405CA Laptop - Unixbench Performance Test


    Here are the results, it is Sempron 3000+ AMD Mobile, 500Gig HDD, 512MB RAM with shared ATI Radeon graphics. # # # # # # # ##### ###### # # #### # # # # ## # # # #&nb........
  • Linux Unix Xorg X Server Intel Extreme i810 Graphics Problem


    Linux Unix Xorg X Server Intel Extreme i810 Graphics Problem(EE) I810(0): No Video BIOS modes for chosen depth. (EE) Screen(s) found, but none have a usable configuration. I have a new Dell PC with one of the latest Intel Extreme Graphics on-board crap. From what I can see any Linux/Unix/FreeBSD versions running XFree86 or Xorg from years ago or the latest version today will have this problem. It's easily corrected FOR MOST people. Go into your........
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