In this article I am going to show that how can we validate the consistency of superblock in XFS.
* I have below xfs filesystem with label testxfs1
[root@client2 ~]# mkfs.xfs -fL testxfs1 /dev/sdc
meta-data=/dev/sdc isize=256 agcount=4, agsize=65536 blks
= sectsz=512 attr=2, projid32bit=1
data = bsize=4096 blocks=262144, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=12800, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
* To check the primary superblock consistency we can run the below command. If its showing the output like XFSB and the label name then our primary superblock is valid one.
[root@client2 ~]# dd if=/dev/sdc bs=512 count=1 | strings
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.000555835 s, 921 kB/s
* If in case, we are not able to see the output like above then we have to go with alternate superblock option for repair.
xfs_repair -vL /dev/sdc
Tip : I have see the scenario in which Cu was supposed to run the repair of 175TB filesystem it took 8 hours to complete the repair on local disks.