[LU-12337] SoM in DoM needs to work transparently

Related — Mon, 22 Feb 2021 21:58:59 +0000

If all data are in DoM (no other components in OSTs), file size should be already stored into MDT object because of DoM.
It doesn't need SoM with DoM, but 'lfs getsom' needs to work transparently same as non-DoM files.
Here is an issue of 'lfs getsom' with DoM.

[root@c01 ~]# mkdir /cache1/dom
[root@c01 ~]# lfs setstripe -L mdt -E 2M /cache1/dom
[root@c01 ~]# pdsh -w c[01-02] lctl set_param ldlm.namespaces.*.lru_size=clear
[root@c01 ~]# pdsh -w es400nv-vm[1-4] "echo 3 > /proc/sys/vm/drop_caches"
[root@c01 ~]# lctl get_param ldlm.namespaces.*MDT0000*.lock_count
ldlm.namespaces.cache1-MDT0000-mdc-ffff97f3bc25d000.lock_count=0

Create an file on c01
[root@c01 ~]# dd if=/dev/zero of=/cache1/dom/file bs=1M count=1
1+0 records in
1+0 records out
1048576 bytes (1.0 MB) copied, 0.00162115 s, 647 MB/s

Run 'lfs getsom' on c02 (different client)
[root@c02 ~]# lfs getsom -s /cache1/nondom/file
/cache1/nondom/file failed to get som xattr: No such file or directory (2)

Also, even 'lfs getsom' works with DoM, we don't want lock cancellation for OST objects after fetch SOM.
Please see below SoM for non-DoM configuration.

[root@c01 ~]# mkdir /cache1/nondom
[root@c01 ~]# lfs setstripe -i 0 /cache1/nondom/
[root@c01 ~]# pdsh -w c[01-02] lctl set_param ldlm.namespaces.*.lru_size=clear
[root@c01 ~]# pdsh -w es400nv-vm[1-4] "echo 3 > /proc/sys/vm/drop_caches"

[root@c01 ~]# lctl get_param ldlm.namespaces.*0000*.lock_count
ldlm.namespaces.cache1-MDT0000-mdc-ffff97f3bc25d000.lock_count=0
ldlm.namespaces.cache1-OST0000-osc-ffff97f3bc25d000.lock_count=0

Create an file on c01
[root@c01 ~]# dd if=/dev/zero of=/cache1/nondom/file bs=1M count=1
1+0 records in
1+0 records out
1048576 bytes (1.0 MB) copied, 0.00185952 s, 564 MB/s
[root@c01 ~]#  lctl get_param ldlm.namespaces.*0000*.lock_count
ldlm.namespaces.cache1-MDT0000-mdc-ffff97f3bc25d000.lock_count=3
ldlm.namespaces.cache1-OST0000-osc-ffff97f3bc25d000.lock_count=1

Even run 'lfs getsom' on c02, no lock cancellation on c01
[root@c02 ~]# lfs getsom -s /cache1/nondom/file
[root@c01 ~]# lctl get_param ldlm.namespaces.*0000*.lock_count
ldlm.namespaces.cache1-MDT0000-mdc-ffff97f3bc25d000.lock_count=3
ldlm.namespaces.cache1-OST0000-osc-ffff97f3bc25d000.lock_count=1

Whamcloud Community JIRA

[LU-12337] SoM in DoM needs to work transparently