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Subject: RE: Performance Issue - burst of writes
Date: Thu, 8 Mar 2007 11:34:07 -0700
Message-ID: <BB375AF679D4A34E9CA8DFA650E2B04E01809850@onstor-exch02.onstor.net>
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Thread-Topic: Performance Issue - burst of writes
Thread-Index: Acdhr5g5gmS0gQ6bT+O349R+kp5mIAAAK+VQ
From: "John Rogers" <john.rogers@onstor.com>
To: "Rex Yuan" <rex.yuan@onstor.com>,
	"dl-cstech" <dl-cstech@onstor.com>

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Variants fo the 2.6 kernel were pretty bursty. Gave us tones o headache
in the past.

=20

________________________________

From: Rex Yuan=20
Sent: Thursday, March 08, 2007 10:29 AM
To: dl-cstech
Subject: Performance Issue - burst of writes

=20

Hello all,=20

=20

I'm working with a customer who is seeing performance issue.

=20

The customer has a cluster of two 2240s and everything is working fine.

Recently, the customer swapped out one of the 2240s and replaced it with
a 2280.

=20

On the 2280, the customer is seeing performance issue.  Asked the
customer to=20

use different linux clients to read and write to the same nfs share. =20

=20

1. Asked the customer to perform read test on the filer.=20
collected stats "evm show stats -r" and "port show loadstats -i 2"
From the stats, read operation seem to be normal=20

2. Asked the customer to perform write test on the filer=20
collected stats "evm show stats -r" and "port show loadstats -i 2"=20
From "port show loadstats -i 2", we see the write operation writes for
10 seconds then=20

pauses for 20 seconds. This behavior continues throughout the entire
write operation.=20

3. Asked the customer to perform read and write test at the same time.=20
collected stats "evm show stats -r" and "port show loadstats -i 2"=20
From "port show loadstats -i 2", we see the same write then pause
behavior.=20

=20

We swapped out the 2280 with the original 2240 and everything worked
fine.

=20

What would cause such "burst of write" behavior? =20

=20

Thank you in advance.

=20

Rex Yuan

ONStor Support


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<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>Variants fo the 2.6 kernel were =
pretty
bursty. Gave us tones o headache in the =
past.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<div>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabindex=3D-1>

</span></font></div>

<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'> Rex =
Yuan <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Thursday, March 08, =
2007
10:29 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> dl-cstech<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> Performance =
Issue - burst
of writes</span></font><o:p></o:p></p>

</div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Hello all, </span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I'm working with a customer who is seeing performance =
issue.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>The customer has a cluster of two 2240s and =
everything is
working fine.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Recently, the customer swapped out one of the 2240s =
and
replaced it with a 2280.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>On the 2280, the customer is seeing performance =
issue.&nbsp;
Asked the customer to </span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>use different linux clients to read and write to the =
same
nfs share.&nbsp; </span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>1. Asked the customer to perform read test on the =
filer. <br>
collected stats &quot;evm show stats -r&quot; and &quot;port show =
loadstats -i
2&quot;<br>
From the stats, read operation seem to be normal <br>
<br>
2. Asked the customer to perform write test on the filer <br>
collected stats &quot;evm show stats -r&quot; and &quot;port show =
loadstats -i
2&quot; <br>
From &quot;port show loadstats -i 2&quot;, we see the write operation =
writes
for 10 seconds then </span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>pauses for 20 seconds.&nbsp;This behavior continues
throughout the entire write operation. <br>
<br>
3. Asked the customer to perform read and write test at the same time. =
<br>
collected stats &quot;evm show stats -r&quot; and &quot;port show =
loadstats -i
2&quot; <br>
From &quot;port show loadstats -i 2&quot;, we see the same write then =
pause
behavior. </span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>We swapped out the 2280 with the original 2240 and
everything worked fine.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>What would cause such &quot;burst of write&quot;
behavior?&nbsp;&nbsp;</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Thank you in advance.</span></font><o:p></o:p></p>

</div>

<div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;<o:p></o:p></span></font></p>

</div>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Rex Yuan</span></font><o:p></o:p></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>ONStor Support</span></font><o:p></o:p></p>

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