[Gluster-users] Gluster-users Digest, Vol 51, Issue 46

[Harry Mangalam]

Hi Ben,

Thanks for the expert advice.

On Fri, Aug 3, 2012 at 2:35 PM, Ben England <bengland at redhat.com> wrote:

> 4. Re: kernel parameters for improving gluster writes on millions of small
> writes (long) (Harry Mangalam)
>
> Harry, You are correct, Glusterfs throughput with small write transfer
> sizes is a client-side problem, here are workarounds that at least some
> applications could use.
>

Not to be impertinent nor snarky, but why is the gluster client written in
this way and is that a high priority for fixing?  It seems that
caching/buffering is one of the great central truths of computer science in
general.  Is there a countering argument for not doing this?

1) NFS client is one workaround, since it buffers writes using the kernel
> buffer cache.
>

Yes, I tried this and I find the same thing.  One thing I am unclear about
tho is whether you can set up and run 1 NFS server per gluster server node.
 ie my glusterfs runs on 4 servers - could I connect clients to each one
using a round robin selection or other load/bandwidth balancing approach?
 I've read opinions that seem to support both yes and no.


>
> 2) If your app does not have a configurable I/O size, but it lets you
> write to stdout, you can try piping your output to stdout and letting dd
> aggregate your I/O to the filesystem for you.  In this example we triple
> single-thread write throughput for 4-KB I/O requests in this example.


I agree again - I wrote up this for the gluster 'hints' <http://goo.gl/NyMXO>
using gzip (other utilities seem to work as well, as do named pipes for
handling more complex output options.

>

[nice examples deleted]
>


> 3) If your program is written in "C" and it uses stdio.h, you can probably
> do setvbuf() "C" RTL call to increase buffer size to something greater than
> 8 KB, which is the default in gcc-4.4.
>

Most of our users are not programmers and so this is not an option in most
cases.

>
> http://en.cppreference.com/w/c/io/setvbuf
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-- 
Harry Mangalam - Research Computing, OIT, Rm 225 MSTB, UC Irvine
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