[Gluster-users] Question regarding write performance issues

[harry mangalam]

Just a guess, but how are the writes being done?  If they're being written in 
zillions of tiny writes, then what you may be seeing is described here:
<http://moo.nac.uci.edu/~hjm/bduc/BDUC_USER_HOWTO.html#writeperfongl>
and the following stanza on named pipes.

This is often the case with the large files being used in NGS/HTS where the 
fasta/fastq files are composed of millions of short (60-100 char) lines of 
characters and are typically written line-by-line.

hjm



On Wednesday, January 16, 2013 02:47:37 PM Ayelet Shemesh wrote:
> Hi to all Gluster experts,
> 
> I have a cluster of 10 machines exposing a volume into which 12 other
> machines do many writes of large files (~100-300MB each).
> In general I'm very happy with gluster. It's a great solution, and is quite
> stable (thanks for the great work!).
> 
> However, I have a problem which I was unable to solve yet, nor find any
> solution to in the documentation or on this list archive.
> 
> When the client machines write locally, and then just copy the files they
> created to the gluster mount - everything works great.
> When the client machines write directly to the gluster mounted volume I get
> a huge performance hit.
> In one specific test case the difference was 20 minutes for the copy and 8
> hours for the direct write.
> 
> I tried to set the iocache attributes of write-behind-window and
> flush-behind, but to no avail.
> 
> I will very much appreciate your help in solving this problem.
> 
> Thanks,
> Ayelet

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