[LU-2029] Can no longer permanently set readcache_max_filesize

• Status: Resolved
• Project: Lustre
• Type: Bug
• Priority: Major
• Reporter: Colin Faber [X] (Inactive)
• Assignee: Jian Yu
• Resolution: Not a Bug
• Severity: 3

Description

While messing around in cache control settings I noticed that I can no longer permanently set readcache_max_filesize with any of the known methods. In all cases I get errors:

[root@mgs ~]# lctl conf_param obdfilter.lustre-OST0003.readcache_max_filesize=1M
error: conf_param: Cannot allocate memory

[root@mgs ~]# lctl conf_param lustre.obdfilter.readcache_max_filesize=1M
Make sure cfg_device is set first.

Per a tips and tricks discussion adilger gave at LUG2010 the recommended method was:

<fs>.<subsys>.readcache_max_filesize however this no longer appears to work.

Am I just doing this wrong or is this really a bug?

-cf

Comments

[Peter Jones]

Yujian

could you please see if this can be reproduced?

thanks

Peter

[Colin Faber [X] (Inactive)]

Hi Peter, it seems format change addresses this:

lctl conf_param <fs>-OST<NNNN>.ost.readcache_max_filesize=NN

So at this point this can be addressed as documentation issue.

-cf

[Jian Yu]

Hello Colin,

I just checked Lustre manual and found the following section described the format clearly:

13.8.3.2. Setting Permanent Parameters
Use the lctl conf_param command to set permanent parameters. In general, the lctl conf_param command can be used to specify any parameter settable in a /proc/fs/lustre file, with its own OBD device. The lctl conf_param command uses this syntax (same as the mkfs.lustre and tunefs.lustre commands):
<obd|fsname>.<obdtype>.<proc_file_name>=<value>

Here are a few examples of lctl conf_param commands:
$ mgs> lctl conf_param testfs-MDT0000.sys.timeout=40
$ lctl conf_param testfs-MDT0000.mdt.identity_upcall=NONE
$ lctl conf_param testfs.llite.max_read_ahead_mb=16
$ lctl conf_param testfs-MDT0000.lov.stripesize=2M
$ lctl conf_param testfs-OST0000.osc.max_dirty_mb=29.15
$ lctl conf_param testfs-OST0000.ost.client_cache_seconds=15
$ lctl conf_param testfs.sys.timeout=40

Caution
Parameters specified with the lctl conf_param command are set permanently in the file system's configuration file on the MGS.

So, I think we can close this ticket.