<div dir="ltr"><div>Hi,</div><div><br></div><div>just a question ...</div><div><br></div>Would SAS disks be better in situation with lots of seek times using GlusterFS?</div><div class="gmail_extra"><br><div class="gmail_quote">2014-09-22 23:03 GMT+03:00 Jeff Darcy <span dir="ltr"><<a href="mailto:jdarcy@redhat.com" target="_blank">jdarcy@redhat.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class=""><br>
> The biggest issue that we are having, is that we are talking about<br>
> -billions- of small (max 5MB) files. Seek times are killing us<br>
> completely from what we can make out. (OS, HW/RAID has been tweaked to<br>
> kingdom come and back).<br>
<br>
</span>This is probably the key point. It's unlikely that seek times are going<br>
to get better with GlusterFS, unless it's because the new servers have<br>
more memory and disks, but if that's the case then you might as well<br>
just deploy more memory and disks in your existing scheme. On top of<br>
that, using any distributed file system is likely to mean more network<br>
round trips, to maintain consistency. There would be a benefit from<br>
letting GlusterFS handle the distribution (and redistribution) of files<br>
automatically instead of having to do your own sharding, but that's not<br>
the same as a performance benefit.<br>
<span class=""><br>
> I’m not yet too clued up on all the GlusterFS naming, but essentially<br>
> if we do go the GlusterFS route, we would like to use non replicated<br>
> storage bricks on all the front-end, as well as back-end servers in<br>
> order to maximize storage.<br>
<br>
</span>That's fine, so long as you recognize that recovering from a failed<br>
server becomes more of a manual process, but it's probably a moot point<br>
in light of the seek-time issue mentioned above. As much as I hate to<br>
discourage people from using GlusterFS, it's even worse to have them be<br>
disappointed, or for other users with other needs to be so as we spend<br>
time trying to fix the unfixable.<br>
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</div>