The option flush-behind makes only the flush call as background. However it waits for all the writes to complete, so that it can return the application errors (if any) happened while syncing them to server. The mail thread you gave for reference [2] also contains discussion about concerns regarding flush-behind not waiting till write-syncs are complete and related explanation.
http://permalink.gmane.org/gmane.comp.file-systems.gluster.user/3361
regards,
Raghavendra.
On Tue, Sep 13, 2011 at 11:59 PM, Paul van Tilburg <paul@xxxxxxxx> wrote:
Hi all,
I have a glusterfs test setup of two servers, each with a brick, that is
replicated. Between the two servers there is a bandwidth limit and I
would like the flush-behind option to handle getting the data to the
other side asynchronously. I am using Debian Squeeze with glusterfs
3.2.3-1. Volume setup:
gluster> volume info
Volume Name: vol1
Type: Replicate
Status: Started
Number of Bricks: 2
Transport-type: tcp
Bricks:
Brick1: glusterserver.home:/tmp/rep
Brick2: glusterclient.home:/tmp/rep
Options Reconfigured:
performance.write-behind-window-size: 32MB
performance.flush-behind: on
However, it seems that when I create a file of 40MB with dd on
glusterclient.home, the close() system call blocks until everything has
fully reached glusterserver.home. This problem has been brought up
before on the users list[1]. I also recall a discussion, back when
flush-behind was default off, that making close non-blocking is
considered to be safe[2].
It seem like I have hit a bug here and would thus like to file a
report. Unless I missed something in the configuration/documentation?
Thanks!
Paul
1: http://www.mail-archive.com/gluster-users@xxxxxxxxxxx/msg01023.html
2: http://comments.gmane.org/gmane.comp.file-systems.gluster.user/3152
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University of Technology, The Netherlands | JID: paul@xxxxxxxx
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Raghavendra G
