Simon Turcotte-Langevin
2016-Feb-03 16:42 UTC
[Gluster-users] GlusterFS behaviour on stat syscall with relatime activated
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) o Sometimes it's instant, sometimes it requires to execute the above command a couple of time 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20160203/22bf69ac/attachment.html>
Pranith Kumar Karampuri
2016-Feb-05 05:54 UTC
[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 > > > > _______________________________________________ > Gluster-users mailing list > Gluster-users at gluster.org > http://www.gluster.org/mailman/listinfo/gluster-users-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20160205/97b14531/attachment.html>