On 02/06/2016 12:19 AM, Simon Turcotte-Langevin wrote:
Good day to you Pranith,
Thank you for your answer, it was exactly this. However, we still have
an issue with RELATIME on GlusterFS.
Stating the file does not modify atime anymore, with quick-read
disabled, however cat-ing the file does not replicate the atime.
This is because of open-behind feature. Disable open-behind with:
"gluster volume set <volname> open-behind off". I believe you will see
the atime behavior you want to see with it. This will reduce the
performance of small file reads (< 64KB). Instead of one lookup over the
network now it will do, lookup + open(This will be sent to both the
replica bricks which updates atime) + read (Only one of the bricks). Let
me know if you want any more information.
Pranith
If I touch manually the file, the atime (or utimes) is replicated
correctly.
So to sum it up:
·[node1] Touch –a file1
oàAccess time is right on [node1] [node2] and [node3]
·[node1] Cat file1
oàAccess time is right on [node1]
oàAccess time is wrong on [node2] and [node3]
Would you have any idea what is going on behind the curtain, and if
there is any way to fix that behavior?
Thank you,
Simon
*From:*Pranith Kumar Karampuri [mailto:pkara...@redhat.com]
*Sent:* 5 février 2016 00:55
*To:* Simon Turcotte-Langevin <simon.turcotte-lange...@ubisoft.com>;
gluster-users@gluster.org
*Cc:* UPS_Development <ups_developm...@ubisoft.com>
*Subject:* Re: [Gluster-users] GlusterFS behaviour on stat syscall
with relatime activated
On 02/03/2016 10:12 PM, Simon Turcotte-Langevin wrote:
Hi, we have multiple clusters of GlusterFS which are mostly alike.
The typical setup is as such:
-Cluster of 3 nodes
-Replication factor of 3
-Each node has 1 brick, mounted on XFS with RELATIME and NODIRATIME
-Each node has 8 disks in RAID 0 hardware
The main problem we are facing is that observation of the access
time of a file on the volume will update the access time.
The steps to reproduce the problem are:
-Create a file (echo ‘some data’ > /mnt/gv0/file)
-Touch its mtime and atime to some past date (touch –d 19700101
/mnt/gv0/file)
-Touch its mtime to the current timestamp (touch –m /mnt/gv0/file)
-Stat the file until atime is updated (stat /mnt/gv0/file)
oSometimes it’s instant, sometimes it requires to execute the
above command a couple of time
atime changes on open call.
Quick-read xlator opens the file and reads the content on 'lookup'
which gets triggered in stat. It does that to serve reads from memory
to reduce number of network round trips for small files. Could you
disable that xlator and try the experiment? On my machine the time
didn't change after I disabled that feature using:
"gluster volume set <volname> quick-read off"
Pranith
On the IRC channel, I spoke to a developer (nickname ndevos) who
said that it might be a getxattr() syscall that could be called
when stat() is called on a replicated volume.
Anybody can reproduce this issue? Is it a bug, or is it working as
intended? Is there any workaround?
Thank you,
Simon
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