{"id":7372,"date":"2018-05-03T23:40:29","date_gmt":"2018-05-03T15:40:29","guid":{"rendered":"http:\/\/rmohan.com\/?p=7372"},"modified":"2018-05-03T23:43:35","modified_gmt":"2018-05-03T15:43:35","slug":"lvm-volume-space-scaling-in-xfs-format-in-centos7","status":"publish","type":"post","link":"https:\/\/mohan.sg\/?p=7372","title":{"rendered":"LVM volume space scaling in XFS format in centos7"},"content":{"rendered":"

LVM volume space scaling in XFS format in centos7<\/strong><\/p>\n

 <\/p>\n

Originally on my CentOS 7 virtual machine, I created 2 partitions:<\/p>\n

sda1 for \/boot
\nsda2 with 1 volume group “centos” with 5 logical volumes:
\n\/
\n\/home
\n\/var
\n\/tmp
\nswap<\/p>\n

I noticed later that I had needed more space from \/home lvm. It was 15GB, it was only using 1.5GB, so I decided to reduce it down to 5GB:<\/p>\n

\n
Code:<\/div>\n
# lvreduce -L 5GB \/dev\/mapper\/centos-home<\/pre>\n<\/div>\n
It said successful so I rebooted.<\/p>\n
Upon reboot, I was sent to emergency mode, and noticed \/home was not listed under df, so I mounted everything in fstab but received an error:<\/p>\n
\n
Code:<\/div>\n
#mount -a \r\nmount: \/dev\/mapper\/centos-home: can't read superblock<\/pre>\n<\/div>\n
So I ran an<\/p>\n
\n
Code:<\/strong><\/div>\n
# xfs_repair \/dev\/mapper\/centos-home<\/strong><\/pre>\n<\/div>\n
It gave me same issues about not being able to read the superblock.<\/p>\n
Oddly enough, the lvdisplay \/dev\/mapper\/centos-home works and now shows LV Size as 5.00GB down from 15.00GB with all the other information listed…<\/p>\n
 <\/p>\n
This article describes the real-time process of adjusting the LVM volume space for xfs under centos7.<\/p>\n
Actual purpose:<\/p>\n
1. Reduce the logical volume \/dev\/mapper\/home from 178G to 10G<\/p>\n
2, empty 168G divided into logical volumes \/dev\/mapper\/root<\/p>\n
Actual process:<\/p>\n
1, back up important data in advance, xfs reduction will lead to data loss<\/p>\n
Backup can use xfsdump, data can also be backed up outside the machine (slightly here)<\/p>\n
Unmount the volume \/dev\/mapper\/home<\/p>\n
[root@localhost ~]# umount \/home<\/p>\n
3, reduce the volume \/ dev \/ mapper \/ homesize (this step will lead to data loss, see the first point)<\/p>\n
[root@localhost ~]# lvreduce -L 5G \/dev\/mapper\/home<\/p>\n
WARNING: Reducing active logical volume to 10.00 GiB.<\/p>\n
THIS MAY DESTROY YOUR DATA (filesystem etc.)<\/p>\n
Do you really want to reduce cl\/home? [y\/n]:y<\/p>\n
Size of logical volume cl\/home changed from 178.25 GiB (45633 extents) to 10.00 GiB (2560 extents).<\/p>\n
Logical volume cl\/home successfully resized.<\/p>\n
4, increase the volume \/dev\/mapper\/root size<\/p>\n
[root@localhost ~]# lvextend -l +100%FREE \/dev\/mapper\/root<\/p>\n
Size of logical volume cl\/root changed from 50.00 GiB (12800 extents) to 218.26 GiB (55874 extents).<\/p>\n
Logical volume cl\/root successfully resized.<\/p>\n
5, adjust the xfs file system size<\/p>\n
[root@localhost ~]# xfs_growfs \/dev\/mapper\/root<\/p>\n
6, re-mount, restore data<\/p>\n
If you directly mount an error message:<\/p>\n
[root@localhost ~]# mount \/dev\/mapper\/home\/home\/<\/p>\n
Mount: \/dev\/mapper\/home: can’t read superblock<\/p>\n
Need to format first<\/p>\n
[root@localhost ~]# mkfs.xfs -f \/dev\/mapper\/home<\/p>\n
Mount after formatting:<\/p>\n
[root@localhost ~]# mount \/dev\/mapper\/home\/home\/<\/p>\n
Recover data after mounting<\/p>\n
This step can be used xfsrestore, or manually copy (refer to the first point)<\/p>\n
 <\/p>\n
 <\/p>\n
$lvremove -v \/dev\/centos\/home<\/p>\n
Which returned the remaining free space to the volume group.<\/p>\n
I then used the $lvextend to extend the \/root lv<\/p>\n
$lvextend -L +900G \/dev\/centos\/root<\/p>\n
And<\/p>\n
$xfs_growfs \/dev\/centos\/root<\/p>\n","protected":false},"excerpt":{"rendered":"
LVM volume space scaling in XFS format in centos7<\/p>\n
 <\/p>\n
Originally on my CentOS 7 virtual machine, I created 2 partitions:<\/p>\n
sda1 for \/boot sda2 with 1 volume group “centos” with 5 logical volumes: \/ \/home \/var \/tmp swap<\/p>\n
I noticed later that I had needed more space from \/home lvm. It was 15GB, it […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[73],"tags":[],"_links":{"self":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/7372"}],"collection":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=7372"}],"version-history":[{"count":4,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/7372\/revisions"}],"predecessor-version":[{"id":7376,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/7372\/revisions\/7376"}],"wp:attachment":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7372"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7372"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7372"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}