[Gluster-devel] Mirrored GlusterFS -- very poor read performance

[Mikhail T.]

[Please, CC replies to me directly as I am not subscribed to the list.
Thank you.]

Joe Landman wrote:
>
>     As mentioned above, four test-files were used for the benchmark:
>
>      1. Small static file - 429 bytes
>      2. Larger static file - 93347 bytes
>      3. Small PHP file (a single php call in it -- to phpinfo() function).
>         Although the file is small, its output was over 64Kb.
>      4. Large PHP file (apc.php). Although the file is larger, its output
>         was only about 12Kb.
>
> One of the questions I routinely ask our customers is what their
> definitions of "small" and "large" are, as their definitions might not
> match what I use for these terms. This is directly relevant in your
> case. What you call "larger" is considered small for GlusterFS. You
> want MB sized IOs to amortize the cost of the fuse system calls.
But these files are representative of what our web-servers will be
serving -- primarily. Though there may be an occasional video, mostly it
is static HTML and "web-size" images, plus PHP-scripts...

Are you saying, GlusterFS is not really for us? We expected to pay
/some/ performance penalty for the features, but the actual numbers are
causing a sticker-shock...

(Writing to GlusterFS is even more horrid -- extracting
thunderbird-24.0.tar.bz2, for example, on a GlusterFS share takes almost
30 minutes, instead of seconds on local FS, but we have very few writes,
and so were willing to ignore that.)

> Did you look at the CSW number? Is it also high?
Around 8K per second, if I'm reading the output of vmstat correctly.

    -mi

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