[LU-2027] writethrough_cache_enable reports erroneous number

• Status: Resolved
• Project: Lustre
• Affects Version/s: Lustre 2.2.0
• Type: Bug
• Priority: Minor
• Reporter: Colin Faber [X] (Inactive)
• Assignee: Jian Yu
• Resolution: Cannot Reproduce
• Severity: 3

Description

When enabled (by default) /proc/fs/lustre/obdfilter/*/writethrough_cache_enable reports an erroneous number which appears to continue to increment upward.

Speaking with Oleg about this, he believes it to be a bug. Per the manual this should either be 1 or 0 indicating enable or disable

Comments

[Peter Jones]

Yujian

Could you please look into this one?

Thanks

Peter

[Jian Yu]

Hello Colin,

I provisioned a test cluster (2 clients, 1 combined MGS/MDS and 1 OSS with 7 OSTs) with Lustre b2_2 build http://build.whamcloud.com/job/lustre-b2_2/17/ and set up a fresh Lustre filesystem by running llmount.sh. After the filesystem was up, I ran the following commands on the OSS node:

[root@fat-intel-4 ~]# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1             20642428   1985276  17608576  11% /
tmpfs                 12298420         0  12298420   0% /dev/shm
/dev/sdc5              2064208    107448   1851904   6% /mnt/ost1
/dev/sdc6              2064208    107448   1851904   6% /mnt/ost2
/dev/sdc7              2064208    107448   1851904   6% /mnt/ost3
/dev/sdc8              2064208    107448   1851904   6% /mnt/ost4
/dev/sdc9              2064208    107448   1851904   6% /mnt/ost5
/dev/sdc10             2064208    107448   1851904   6% /mnt/ost6
/dev/sdc11             2064208    107448   1851904   6% /mnt/ost7
[root@fat-intel-4 ~]# lctl get_param obdfilter.*.writethrough_cache_enable
obdfilter.lustre-OST0000.writethrough_cache_enable=1
obdfilter.lustre-OST0001.writethrough_cache_enable=1
obdfilter.lustre-OST0002.writethrough_cache_enable=1
obdfilter.lustre-OST0003.writethrough_cache_enable=1
obdfilter.lustre-OST0004.writethrough_cache_enable=1
obdfilter.lustre-OST0005.writethrough_cache_enable=1
obdfilter.lustre-OST0006.writethrough_cache_enable=1
[root@fat-intel-4 ~]# lctl set_param obdfilter.*.writethrough_cache_enable 0
obdfilter.lustre-OST0000.writethrough_cache_enable=0
obdfilter.lustre-OST0001.writethrough_cache_enable=0
obdfilter.lustre-OST0002.writethrough_cache_enable=0
obdfilter.lustre-OST0003.writethrough_cache_enable=0
obdfilter.lustre-OST0004.writethrough_cache_enable=0
obdfilter.lustre-OST0005.writethrough_cache_enable=0
obdfilter.lustre-OST0006.writethrough_cache_enable=0
[root@fat-intel-4 ~]# lctl get_param obdfilter.*.writethrough_cache_enable
obdfilter.lustre-OST0000.writethrough_cache_enable=0
obdfilter.lustre-OST0001.writethrough_cache_enable=0
obdfilter.lustre-OST0002.writethrough_cache_enable=0
obdfilter.lustre-OST0003.writethrough_cache_enable=0
obdfilter.lustre-OST0004.writethrough_cache_enable=0
obdfilter.lustre-OST0005.writethrough_cache_enable=0
obdfilter.lustre-OST0006.writethrough_cache_enable=0
[root@fat-intel-4 ~]# lctl set_param obdfilter.*.writethrough_cache_enable 1
obdfilter.lustre-OST0000.writethrough_cache_enable=1
obdfilter.lustre-OST0001.writethrough_cache_enable=1
obdfilter.lustre-OST0002.writethrough_cache_enable=1
obdfilter.lustre-OST0003.writethrough_cache_enable=1
obdfilter.lustre-OST0004.writethrough_cache_enable=1
obdfilter.lustre-OST0005.writethrough_cache_enable=1
obdfilter.lustre-OST0006.writethrough_cache_enable=1
[root@fat-intel-4 ~]# lctl get_param obdfilter.*.writethrough_cache_enable
obdfilter.lustre-OST0000.writethrough_cache_enable=1
obdfilter.lustre-OST0001.writethrough_cache_enable=1
obdfilter.lustre-OST0002.writethrough_cache_enable=1
obdfilter.lustre-OST0003.writethrough_cache_enable=1
obdfilter.lustre-OST0004.writethrough_cache_enable=1
obdfilter.lustre-OST0005.writethrough_cache_enable=1
obdfilter.lustre-OST0006.writethrough_cache_enable=1

As we can see, the value of writethrough_cache_enable was correct.

I also did the same test on the following Lustre builds:
Lustre Build: http://build.whamcloud.com/job/lustre-master/898/
Lustre Build: http://build.whamcloud.com/job/lustre-b2_3/24/
Lustre Build: http://build.whamcloud.com/job/lustre-b2_2/21/

All worked properly.

Could you please tell me what tests/operations you performed to hit the erroneous number issue? Thanks.

[Peter Jones]

Colin

Could you also please clarify whether this is a vanilla 2.2 release or whether there have been any modifications made to it?

Thanks

Peter

[Jian Yu]

Close old ticket. If the issue occurs again, please feel free to reopen the ticket.