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<div>Anand,</div>
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<div>Thanks for the response.</div>
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<div>So am I correctly interpreting your answer as saying that it caches (statically sized) 128KB pages in the configured memory space?</div>
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<div>In other words, is it accurate to say that if I configure performance.cache-size to be 1GB, it will store the eight most recently used 128KB pages in the cache?</div>
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<div>Thanks again.</div>
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Regards,
<div>Jon Heese</div>
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On Mar 12, 2015, at 1:20 PM, "Anand Avati" <<a href="mailto:avati@gluster.org">avati@gluster.org</a>> wrote:<br>
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<div dir="ltr">The cache works by remembering 128KB "pages" within files. Effectively "blocks" in your terminology.<br>
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Thanks</div>
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<div class="gmail_quote">On Wed, 11 Mar 2015 at 12:36 Jon Heese <<a href="mailto:jonheese@jonheese.com">jonheese@jonheese.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hello,<br>
<br>
I have a two-server, two-brick (one brick per server) replicated Gluster<br>
3.6.2 volume, and I'm interested in the 'performance.cache-size' option<br>
and how that read cache works.<br>
<br>
My volume currently stores a handful of ~500GB image files, which are<br>
then fed to an iSCSI daemon to serve up datastores and other<br>
miscellaneous iSCSI disks to servers over an iSCSI network.<br>
<br>
I have about 14GB of unutilized (minus system cache/buffers) memory on<br>
the gluster servers (which are also the gluster clients, in this case)<br>
which I'd like to utilize to improve the read performance of this volume.<br>
<br>
So since my files are are well over the "tens of GB" mark, I'm curious:<br>
Does the Gluster read cache work at the block level -- i.e. caching<br>
*blocks* that are likely to be read -- or does it work at the file level<br>
-- caching *files* that are likely to be read? Obviously, the latter<br>
might work well for me, but the former is likely not very useful.<br>
<br>
I've tried searching around for details on how this works, but short of<br>
diving into the code itself (which is likely beyond my skill level and<br>
time allowance), I haven't been able to find the answer to this question.<br>
<br>
If I've misunderstood how any of this is supposed to work, please feel<br>
free to correct me. Thanks in advance!<br>
<br>
Regards,<br>
Jon Heese<br>
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