It is unfortunate that LXC's dir mode is completely insecure and allows way too much information from the host to be seen. I wonder if there will eventually be a way to break into the host filesystem or other container's storage?
OpenVZ better security:
[root@ev ~]# cat /proc/mdstat
cat: /proc/mdstat: No such file or directory
/dev/simfs 843G 740G 61G........
The strange thing is that usually the first install or two will work on any new machine but then it suddenly won't. I had this experience on QEMU 2.13 on a different machine. There is something finicky or buggy about the CUCM installer even when choosing the same virtual hardware specs.
QEMU PC emulator version 0.12.1 (qemu-kvm-0.12.1.2-2.506.el6_10.1), Copyright (c) 2003-2008 Fabrice Bellard
chroot which stands for change root allows you to virtually operate in another operating system even though you haven't booted it. It is commonly used to deploy new distros, applications and to fix a broken Linux/Unix install or prep a new system image without having to physically boot the drive or disk.
So in this example let's say we have a drive that has a Linux OS installed on /dev/sdb1 and we have mounted this partition on /mnt/sdb1
The key point is to edit the &quo........
Do you hate how Centos 7 defaults to allocating most of your valuable space to /home even though it is a production server?
Here is a quick guide on how to take back that space live, while online (of course make sure you have backups just in case something goes wrong!):
First we will reduce our home dir by 100G:
lvreduce -L -100G /dev/mapper/centos-home
WARNING: Reducing active and open logical volume to ........
size = the amount of RAM (m for megabytes)
/mnt/ram = the mount location of the ram disk (change to the path you want it mounted to)
mount -t tmpfs -o size=4096m tmpfs /mnt/ram/
Example test in an old server:
You can see that when reading if you don't specify bs1=M the read speeds are several times slower (eg. 450MB/s vs 2.1GB/s)
mount -t tmpfs -o size=4096m tmpfs /mnt/ram/^C
INQUIRY: [ASUS ][BW-16D1HT ][3.00]
GET [CURRENT] CONFIGURATION:
Mounted Media: 11h, DVD-R Sequential
Media ID: RITEKF1&n........
Error: Unable to apply new quota values: quota not running
Container start failed (try to check kernel messages, e.g. "dmesg | tail")
Killing container ...
Container was stopped
Error: Unable to apply new quota values: quota not running
Can't umount /vz/private/123123: Invalid argument
[root@rtt 123123]# vzquota on 123123
vzquota : (error) Can't open quota file for id 123123, maybe you need to reinit........
guestmount -a kvmuserscra.img -m /dev/sda1 mount
libguestfs: error: mount_options: /dev/sda1 on / (options: ''): mount: unknown filesystem type 'ntfs'
guestmount: '/dev/sda1' could not be mounted.
guestmount: Did you mean to mount one of these filesystems?
guestmount: /dev/sda1 (ntfs)
guestmount: /dev/sda2 (ntfs)
yum -y install ntfs-3g
This container won't start after exhausting its memory. There are no relevant or helpful messages in dmesg or vzctl.log as well. Standard troubleshooting such as disabling PPP etc has not helped.
2017-07-06T23:33:29-0400 vzctl : CT 888171 : Locked by: pid 166029, cmdline vzctl start 888171
2017-07-06T23:33:29-0400 vzctl : CT 888171 : Container already locked
2017-07-06T23:33:29-0400 vzctl : CT 888171 : Container was stopped
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........
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)
Here is a simple MP3 player and now there's a reason to understand why the supplied cable has some kind of capacitor and is very short. These devices can be VERY finicky and any voltage fluctuation or difference is enough to cause issues.
Take for example the error messages from Linux Mint:
[804829.895414] usb 1-1: USB disconnect, device number 11
[806961.109030] usb 1-1: new high-speed USB device number 12 using xhci_hcd........
1.) Replicate the number of partitions in your new drives.
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).........
In short the solution is just to use vgremove for the actual /dev/mapper device:
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........
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........
Cannot even "Browse Network" when clicking on "Windows Network"
Unable to mount location
Failed to retrieve share list from server: No such file or directory
[2017/02/14 00:16:44.271314, 0] ../source3/nmbd/nmbd.c:58(terminate)
Got SIGTERM: going down...
[2017/02/13 17:35:41.797944, 0] ../lib/util/become_daemon.c:124(daemon_ready)
The only solution after trying many suggestions was to simply restart the "vz" service (definitely not preferable).
Even doing an ifdown and ifup for venet0 did not help.
Bringing up interface venet0:
Configuring interface venet0:
net.ipv4.conf.venet0.send_redirects = 0
RTNETLINK answers: Network is down
Some errors from log:
CPT ERR: d2dc60........
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).
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........
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!
eg. 32bit HN:
total used free shared buffers cached
rm: remove regular file `/vz/lock/1200.lck'? y
vzctl start 1200
Container already locked
vzctl start 1200
Starting container ...
vzquota : (error) can't lock quota file, some quota operations are performing for id 1200
vzquota on failed 
vzquota off 1200
vzctl start 1200
vzquota on 1200
root@rttbox ~]# vzquota off 1200
vzquota : (........
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........
#count=10000 makes an image of 10000MB make sure your image is at least the same as your existing
dd if=/dev/zero of=yourimage.img bs=1M count=10000
# losetup -fv newimage.raw
# fdisk -cu /dev/loop0
# kpartx -a /dev/loop0
# dd if= of=/dev/mapper/loop0p1
# e2fsck -f /dev/mapper/loop0p1
# resize2fs /dev/mapper/loop0p1
# a lot of guides tell you to edit /etc/fst........
vzquota : (error) Quota on syscall for id 42131: No such file or directory
vzquota on failed 
mv quota.42131 quota.42131-disable
vzctl start 42131
Initializing quota ...
Container is mounted
Adding IP address(es):
Setting CPU units: 1000
Container start in progress...
mkdir: cannot create directory 'test': Disk quota exceeded
You are out of inodes usually:
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/simfs 200000 200000 0 100% /
Container is currently mounted (umount first)
The container is stuck in the "mounted" state, you must manually start it to get it out of that state (there is no umount option as implied by OpenVZ vzctl).........
When trying to reboot this Centos 5 container, it gets stuck as "mounted" and requires a manual start command, here is what dmesg shows:
[424458.173252] VE10000: no allowed mount options found for device 0:21
[424458.177970] proc: unrecognized mount option "relatime" or missing value
[424460.297663] CT: 10000: stopped
[426663.466433] CT: 10000: started........
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........
Filesystem Size Used Avail Use% Mounted on
50G 1.2G 46G 3% /
tmpfs 7.8G 0&nb........
I backed up everything in the /mnt/sd_card directory thinking that some dataloss could occur for some reason but purposely left my microSDHC unbacked up thinking that "it won't touch that since it's external" and Samsung's and other manufacturers website even say this (that it won't be affected and not to worry etc).
Apparently I was wrong, my microSD was "undetected" and asked to be formatted after the upgrade (there goes 3-months worth of family photos). No........
fdisk -lu VPS.img
last_lba(): I don't know how to handle files with mode 81ed
You must set cylinders.
You can do this from the extra functions menu.
Disk VPS.img: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End ........
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........
umount: /home/diret/mount: device is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))
I tried everything (fusermount -u) to unmount it but the only thing that worked was actually doing this:
ps aux|grep sshfs
Then I identified the sshfs connection and did:
kill -kill pid........
I've only used it on Centos, soI thought I'd make a quick Debian guide:
Install the DRBD Package
apt-get install drbd8-utils
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
Use 'apt-get autoremove' to remove them.
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: md127: raid array is not clean -- starting background reconstruction
raid1: raid set md127 active with 1 out of 2 m........
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........
Adding IP address(es): 192.168.5.8 192.168.5.9
Setting CPU units: 1000
Error: undump failed: Invalid argument
Error: iptables-restore exited with 2
Error: Most probably some iptables modules are not loaded
Error: rst_restore_net: -22
Container start failed
Stopping container ...
Container was stopped
Container is unmounted
Error: Failed to undump VE
vzquota : (erro........
This is a great way to use your ftp server space, for example on your web hosting account (althoughI believe many hosts don't allow storage like this), but if you have a VPS/Dedicated Server etc.., this would be perfect. Imagine how easy it is to work with an ftp account that you can just mount as a normal partition or directory in Linux, it would be great for backups etc..
curlftpfs - mount a ftp host as a local directory
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........
I have no idea why but mkfs.ext3 defaults to a patheticlly small blocksize of 1024 bytes/1KB (kilobyte). That means the maximum filesize is ONLY 16GB! With 2KB/2048 bytes you get a 256 GB maximum filesize, and with 4KB/4096 bytes you get 2TB!
I finally noticed/paid attention to this after realizing that with rsync and scp that no file larger than 17GB could be transferred. I then realized it must be a file size limit on the partition.
Here is what tune2fs tol........
Proxmox has made this free utility to backup running OpenVZ containers. It's a great program which is actually just a PERL script but gets the job done. This program is not 100% required because all it really does is cp -a from your container's path as far as I know but it is still good to have uniformity to how you backup your containers.
For RPM distros such as Centos/RHEL/Fedora etc.. download and install this:
./ntfs-3g /dev/sda1 /mnt -o force
Unexpected sectors per cluster value (127).
Failed to mount '/dev/sda1': Invalid argument
The device '/dev/sda1' doesn't seem to have a valid NTFS.
Maybe the wrong device is used? Or the whole disk instead of a
partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?
This is happening on a system I've come across an HP 6930P running Windows XP Professional. The partition appears to be very norm........
heartbeat is stopped for some reason
Anyway hnode2 was active and the services are running fine but I see heartbeat has been stopped somehow.
Here is the last log I see of heartbeat:
Sep 9 17:15:32 hnode2 heartbeat: : info: MSG stats: 9/1762471 ms age 0 [pid16738/MST_CONTROL]
Sep 9 17:15:32 hnode2 heartbeat: : info: cl_malloc stats: 716/51784021 152624/74519 [pid16738/MST_CONTROL]
Sep 9 17:15:32........
Mounting NTFS in UnixJust a quick tutorial to mount your NTFS volumes in Unix (FreeBSD/Linux)
[quote:4a9de7bf80]mount -t ntfs -o umask=0 /dev/your_partition /mnt/your_mount_point[/quote:4a9de7bf80]
[b:4a9de7bf80]-o umask=0[/b:4a9de7bf80] is to ensure all users can access the mounted partition (otherwise don't use it and only root can access the mounted partition)
[b:4a9de7bf80]-t ntfs[/b:4a9de7bf80] is simple because it just lets mount kno........
sed is great for pattern matching or retrieving linesHere is a cool example
Say you type df:
The output would be something like:
[quote:3bb8d51437]Filesystem 1k-blocks Used Available Use% Mounted on
/dev/hda2 1712432 1206664 418780 75% /
/dev/hda1 31201 10505 19085 36% /boot
none 30932 0 30932 0% /dev/shm
top - 09:34:12 up 2 days, 20:57, 2 users, load average: 1.83, 1.99, 2.03
Tasks: 59 total, 2 running, 57 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.3%us, 0.0%sy, 0.0%ni, 0.0%id, 99.7%wa, 0.0%hi, 0.0%si, 0.0%st
That 99.7% wa is iowait, it means the server is waiting for a process to complete an IOoperation or in plain English, there is a delay in........
When trying to even cd or ls the mounted OCFS2 partition it crashes. Ithink this is a combination of VMWare Server's problem and the way I mounted and symlinked to it.
More than anything this shows the problem and lack of forsight with VMWare, but also that OCFS2 is easily crashed if you do strange things.
Output of /var/log/messages for OCFS2
Apr 10 15:57:45 localhost kernel: [84331.691258] Modules linked in: vmnet vmci vmmon ocfs2_stac........
There's a lot of information and guides on OCFS2 for RHELand Centos Linux but the package setup and configuration is slightly different and this has thrown some people off.
You should install the following packages to get started:
apt-get install ocfs2-tools ocfs2console
In RHEL/Centos the main configuration file is located in /etc/sysconfig/o2cb
However in Debian based Linux it is located........