The file systems are typically ext4. Running current patches on Redhat 6.9.
This isn't something we routinely look at, but after
a couple of VMware systems showing scsi errors, I noticed almost
every Redhat 6 system will show some disk errors from
something like fsck -n / or same on /var
# fsck -n /
fsck from util-linux-ng 2.17.2
e2fsck 1.41.12 (17-May-2010)
Warning! /dev/sda1 is mounted.
Warning: skipping journal recovery because doing a read-only filesystem check.
/dev/sda1 contains a file system with errors, check forced.
Pass 1: Checking inodes, blocks, and sizes
Deleted inode 22413413 has zero dtime. Fix? no
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Block bitmap differences: -46708735 -(46712832--46712840) +79201706 +79201715 -79201836 -79202321 -(79234801--79234855) +(79234914--79234968)
Free blocks count wrong (42767651, counted=42765254).
Inode bitmap differences: -22413413
Free inodes count wrong (25523840, counted=25523326).
/dev/sda1: ********** WARNING: Filesystem still has errors **********
/dev/sda1: 526720/26050560 files (0.2% non-contiguous), 61424349/104192000 blocks
The SAN backend for these VMs, nor the host boxes, have no alerts or warnings.