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


From: Mikhail T.
Subject: Re: [Gluster-devel] Mirrored GlusterFS -- very poor read performance
Date: Fri, 03 Jan 2014 01:59:39 -0500
User-agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0

[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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