[Gluster-users] What is it with trusted.io-stats-dump?

[Jeevan Patnaik]

Hi,

>From strace, I can see the system calls setxattr and getxattr.

Two things I don't understand is:

1. how does the file got created so quickly, from where it read the stats.
2.why is the added attribute missing if I check with getfattr?

Regards,
Jeevan.




On Nov 13, 2017 12:40 PM, "Amar Tumballi" <atumball at redhat.com> wrote:



On Mon, Nov 13, 2017 at 12:14 PM, Jeevan Patnaik <g1patnaik at gmail.com>
wrote:

> Hi,
>
> I am trying to understand how the extended attribute trusted.io-stats-dump
> works.
>
> setfattr -n trusted.io-stats-dump -v /tmp/gluster_perf_stats/io-stats-pre.txt
> /mnt/gluster/gv0_glusterfs
>
> I can see that the io-stats-pre.txt is created. But how and what happened
> in the background?
>
> And why I can't I see the attribute with getfattr again?
>
>
That is because 'trusted.io-stats-dump' is one of the many Virtual key
GlusterFS handles.

As GlusterFS is a filesystem, the way to interact with it is through system
calls. GlusterFS has some options for debugging in-built using 'setxattr()'
and 'getxattr()' syscall interface, and they are called 'virtual keys'.

Regards,
Amar



> getfattr -dm- /mnt/gluster/gv0_glusterfs
> # file: mnt/gluster/gv0_glusterfs
> trusted.glusterfs.dht.commithash="3480667945 <03480%20667%20945>"
>
> Regards,
> Jeevan.
>
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-- 
Amar Tumballi (amarts)
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