[LU-14565] Changing recordsize of OST Breaks 'df' (lfs df works correctly)

Related — Fri, 13 May 2022 13:38:23 +0000

Changing recordsize from 1M(default) to 32K breaks the 'df' output. 'lfs df' however works correctly. The 'size', 'used' and 'Avail' fields of the 'df' output shows wrong values. This is seen immediately. Switching record size back to 32K, it was observed that it fixes the issue.

Steps to recreate:

$ df -h 
$ cp <file> /mnt/lustre
$ df -h 
$ zfs set recordsize=32768 gpool/data
$ df -h /* Almost immediately starts showing wrong results, lfs df is good */
$ zfs set recordsize=1048576 gpool/data
$ df -h /* Results are good again */

Details

# df -h
Filesystem Size Used Avail Use% Mounted on
...
gpool/metadata 77M 3.0M 72M 5% /mnt/zfsmdt
gpool/data 76M 3.0M 71M 5% /mnt/zfsost
192.168.50.72@tcp:/lustre 76M 3.0M 71M 5% /mnt/lustre

# lfs df -h
UUID bytes Used Available Use% Mounted on
lustre-MDT0000_UUID 76.6M 3.0M 71.6M 5% /mnt/lustre[MDT:0]
lustre-OST0000_UUID 76.0M 3.0M 71.0M 5% /mnt/lustre[OST:0]
filesystem_summary: 76.0M 3.0M 71.0M 5% /mnt/lustre

Verify recordsize

# zfs get recordsize gpool/data
NAME PROPERTY VALUE SOURCE
gpool/data recordsize 1M local

# cp configure /mnt/lustre
# ls -ali configure
670300 -rwxr-xr-x 1 root root 1346008 Mar 26 11:49 configure

# df -h
Filesystem Size Used Avail Use% Mounted on
...
gpool/metadata 75M 3.0M 70M 5% /mnt/zfsmdt
gpool/data 76M 5.0M 69M 7% /mnt/zfsost
192.168.50.72@tcp:/lustre 76M 5.0M 69M 7% /mnt/lustre
# lfs df -h
UUID bytes Used Available Use% Mounted on
lustre-MDT0000_UUID 74.6M 3.0M 69.6M 5% /mnt/lustre[MDT:0]
lustre-OST0000_UUID 76.0M 5.0M 69.0M 7% /mnt/lustre[OST:0]
filesystem_summary: 76.0M 5.0M 69.0M 7% /mnt/lustre

Change the record size

zfs set recordsize=32768 gpool/data

# df -h
...
gpool/metadata 75M 3.0M 70M 5% /mnt/zfsmdt
gpool/data 77M 5.1M 70M 7% /mnt/zfsost
192.168.50.72@tcp:/lustre 2.4G 163M 2.2G 7% /mnt/lustre <~~~ Bumps to 2.4GB

# lfs df -h
UUID bytes Used Available Use% Mounted on
lustre-MDT0000_UUID 74.6M 3.0M 69.6M 5% /mnt/lustre[MDT:0]
lustre-OST0000_UUID 76.8M 5.1M 69.7M 7% /mnt/lustre[OST:0]
filesystem_summary: 76.8M 5.1M 69.7M 7% /mnt/lustre

Whamcloud Community JIRA

[LU-14565] Changing recordsize of OST Breaks 'df' (lfs df works correctly)