Hi Ed and Oleksandr,<div><br></div><div>Thanks for the prompt replies!</div><div><br></div><div>There's no swapping or paging out (si=0 consistently in the vmstat output). Plenty of free memory during the reading process.</div>
<div><br></div><div>I'm using 24 VM's (running under OpenStack) in 4 data centers. Each VM has two 2 VCPU's, 4GB of memory, and 50GB of disk space (40GB for Tahoe storage). All VM's were dedicated to the Tahoe experiments.</div>
<div><br></div><div>I set up a separate Tahoe client to do the performance measurements through the Thaoe command line tools so that I could collect elapsed time easily. For example,</div><div><br></div><div>$ tahoe create-alias grid</div>
<div>$ time tahoe cp 383MB.mov grid:</div><div>$ time tahoe cp grid:383MB.mov t.mov</div><div>$ cmp 383MB.mov t.mov</div><div><br></div><div>I'll run the same tests through the Web interface and check out the performance pages - thanks!</div>
<div><br></div><div>Robin</div><div><br><div class="gmail_quote">On Mon, Mar 4, 2013 at 11:09 AM, Oleksandr Drach <span dir="ltr"><<a href="mailto:luckyredhot@gmail.com" target="_blank">luckyredhot@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><b>Robin,</b><div>I think your grid speed is quite good.</div><div>Could you please briefly provide your hardware details?</div>
<div><br></div><div>You can additionally check every download operation on <a href="http://yournode.com:3456/status/" target="_blank">Status Page</a>. Click on Status column and you'll find <a href="http://yournode.com:3456/status/down-0" target="_blank">more details</a>.</div>
<div><a href="http://yournode.com:3456/status/down-0/timeline" target="_blank">Timeline</a> is also may be very useful.</div><div><br></div><div>You can find further readings on Tahoe-Lafs performance <a href="https://tahoe-lafs.org/trac/tahoe-lafs/wiki/Performance" target="_blank">here</a> and <a href="https://tahoe-lafs.org/trac/tahoe-lafs/wiki/Performance/Old" target="_blank">there</a>.</div>
<div><br></div><div><b>Zooko,</b></div><div>I think adding "real" performance numbers to the <a href="https://tahoe-lafs.org/trac/tahoe-lafs/wiki/Performance" target="_blank">Performance page</a> will be really helpful for a lot of people.<br>
<div><br></div><div><br></div><div><div><div><em>Sincerely,<br>Oleksandr Drach,</em></div>
<div><br><em>e-mail: </em><a href="mailto:luckyredhot@gmail.com" target="_blank"><em>luckyredhot@gmail.com</em></a><em>.</em><br></div></div><div><div class="h5">
<br><br><div class="gmail_quote">2013/3/4 Ed Kapitein <span dir="ltr"><<a href="mailto:ed@kapitein.org" target="_blank">ed@kapitein.org</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi Robin,<br>
<br>
I am quiet new too, and i ran into a "out of memory" situation, while<br>
reading a large file.<br>
Did you check to see if the reading machine starts swapping?<br>
( you can check with top )<br>
That could make the machine and the reading real slow.<br>
<br>
Kind regards,<br>
Ed<br>
<div><div><br>
On Mon, 2013-03-04 at 10:45 -0500, Robin Chen wrote:<br>
> Hi,<br>
><br>
><br>
> I have recently started my experiments with Tahoe and deployed 24<br>
> Tahoe storage nodes in 4 data centers (using 9 out-of 24 coding), but<br>
> I'm running into a performance problem.<br>
><br>
><br>
> I'm new to this email list, so I'm not sure if this problem has been<br>
> discussed before or not.<br>
><br>
><br>
> I would expect the "reading" performance (reading 9 shares) to be<br>
> better than the "writing" performance (writing 24 shares in 4<br>
> geographically-distribute data centers), but the reading time is<br>
> typically two times longer in most of my tests with files > 300MB.<br>
><br>
><br>
> For example, for a file size of 383MB, I'm getting about 16Mbps in<br>
> throughput for writing, but only about 8.8Mbps in reading.<br>
><br>
><br>
> Any possible explanation?<br>
><br>
><br>
> Thanks!<br>
><br>
><br>
> Robin<br>
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