<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>One more reason I can't wait for ZFS to become available as lustre's underlying filesystem :)</div><br><div><div>On Jan 23, 2010, at 11:47 PM, Scott Adametz wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Any possibility to redirect Lustre's OSS Cache or portions of the Linux pagecache to a location other than
RAM such as to an internal SSD (perhaps even two in RAID0). I ask
because the servers we have available (read: second hand servers) for OSSs physically
max out at 8GB RAM. <br>
<br>The wiki states: <i>"It uses a regular Linux pagecache to store the
data."</i> I looked into pagecache and pdflush tunables but found
little on directing the actual location of the cached content as it
tends to focus
heavily on tuning timing of writes-<b>to</b>-disk vs reads. Yes, I
understand the absurdity of trying to redirect RAM cached content back
to "disk" but with rapidly evolving SSD design and performance it
actually makes some sense in this case for Lustre cache data. Obviously I would prefer to redirect
<u>only</u> Lustre OSS cache data and not the entire Operating System page cache. <br><br>While an SSD is nowhere near as quick as RAM, it would still seem
beneficial to have more frequently viewed content available for reads even from an
SSD vs a spinning disk, especially with our use case (HD video editing
and playback). Until SSD prices come down to reasonable levels and we can afford to replace all spinning disks with SSDs, any little bit helps ;-)<br>
<br>In sum: just a thought to be able to designate, in Lustre configs, an additional low-latency "swap" or "cache" location on
the OSSs. Adding one SSD to each OSS sure beats having to buy new servers with more RAM capacity or using all SSD
drives and blowing the budget...<br><br>Thanks for the time, <br><br clear="all">Scott Adametz<br><font size="1">Systems
Engineer<br>
Big Ten Network<br>FOX Networks Group<br></font><font color="#888888"><font size="1"><a href="mailto:scott.adametz@fox.com" target="_blank">scott.adametz@fox.com</a></font></font>
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