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I have openstack environment with centos 7 and lvm, added new 100gb to instance. Now I wan't to move home var and usr to the new disk, I have successfully moved home and var to new disk but I don't understand why usr does not load from new disk, even I have it in fstab.

df -h:

/dev/mapper/vg01-root     43G  1,3G   42G   3% /
 devtmpfs                 3,9G     0  3,9G   0% /dev
 tmpfs                    3,9G     0  3,9G   0% /dev/shm
 tmpfs                    3,9G  8,4M  3,9G   1% /run
 tmpfs                    3,9G     0  3,9G   0% /sys/fs/cgroup
 /dev/mapper/vg01-tmp     2,0G  6,1M  1,8G   1% /tmp
 /dev/mapper/vgdata-var    20G  152M   19G   1% /var
 /dev/mapper/vgdata-home   58G   53M   55G   1% /home
 /dev/vda1                509M  185M  325M  37% /boot
 tmpfs                    799M     0  799M   0% /run/user/1000

fstab:

/dev/mapper/vg01-root   /                       xfs     defaults        0 0
UUID=1b2b970c-defc-4ae6-94a7-38fd0141ff3e /boot                   xfs     defaults        0 0
/dev/mapper/vg01-swap   swap    swap    defaults        0 0
/dev/mapper/vg01-tmp    /tmp    ext4    defaults        0 0
/dev/mapper/vgdata-home /home   ext4    defaults        0 0
/dev/mapper/vgdata-var  /var    ext4    defaults        0 0
/dev/mapper/vgdata-usr  /usr    ext4    defaults        0 0

I have made new var, usr and home under /mnt and then copied each to its own folder, others work fine except usr. I have rebooted many times, no luck

  • When existing OS didnt have /usr partition and add new partition as /usr. Sure, It didnt work. /usr contained many executable commands.Existing OS got /home and /var partition. You can move to new partition /home and /var.Did you copy /usr to new partition before you mounted as /usr new partition? You should delete all files in existing /usr.Can you mount it without empty /usr? – supriady Jan 9 '17 at 8:58
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    Does CentOS still allow /usr to be on a spare partition? I thought that functionality had been abandoned a couple of years ago. – roaima Jan 9 '17 at 8:59
  • I'm not actually sure, but then I must install whole system to the new disk, because my operator has 100gb "fast" system disk offered on some open stack instances, thought this is not "regular" image/disk, you can't make image or snapshot from it, and it is only meant for system. So I bought some disk space for my own data which I can create snapshot etc.... – Diamonte Jan 9 '17 at 9:04
  • Backup /usr successfully and restore to new partition.Delete all files and subdirectories from existing /usr.Maybe it worked.Maybe you can rename existing /usr to /usr.old, – supriady Jan 9 '17 at 9:07
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According to a number of articles I've read over the last couple of years, putting /usr on its own partition is not recommended. More to the point, parts of the user-land OS subsystems will fail (mostly, silently).

References

To be fair, one of these is from Fedora, but the article goes to some lengths to point out that this isn't a Fedora-specific change.

  • Thank for your answer. I reconsider this and think couble more times how to take advance from "free" system disk (which is supposed to be fast), but you can't create image, snapshot from it. So basically all critical data should be located in my data disk, in this case the SAS disk you can backup and/or create images from it from the open stack panel, if need. I could move possibly entire system to the SAS (paid disk) but if there is a way to use that system disk along this one, it would be great. Reason for trying to get those to new disk is I'm installing cPanel on this server – Diamonte Jan 9 '17 at 10:48

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