On Tue, Sep 28, 2010 at 11:15 AM, Eric Shubert <span dir="ltr">&lt;<a href="mailto:ejs@shubes.net">ejs@shubes.net</a>&gt;</span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Alan Dayley wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">
Maybe <a href="http://www.otisworldwide.com/" target="_blank">http://www.otisworldwide.com/</a> ?<br>
<br>
(Sorry, couldn&#39;t resist.)<br>
<br>
Side track: What does the word &quot;elevator&quot; mean in the context of RAID?<br>
Ha!</div></blockquote>
<br>
In the linux kernel, the I/O scheduler is referred to as the elevator. It can be set to one of 4 values in the 2.6 kernel using the elevator= kernel parameter at boot time. Each block device&#39;s scheduler is determined by the value in /sys/block/&lt;device&gt;/queue/scheduler<br>

$ cat /sys/block/sda/queue/scheduler<br>
noop anticipatory deadline [cfq]<br>
<br>
You can change a device&#39;s elevator on the fly by doing:<br>
# echo deadline &gt;/sys/block/sda/queue/scheduler<br>
<br>
I&#39;m just wondering which value gives the best performance when using software raid-1, or if the choice depends more on the type of load that&#39;s being processed.<div><div></div><div class="h5"><br></div></div></blockquote>
<div>Thank you, Eric.  I did not know about that kernel setting.</div><div><br></div><div>Alan</div><div> </div></div>