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Subject: Performance Issue - burst of writes
Date: Thu, 8 Mar 2007 11:28:40 -0700
Message-ID: <BB375AF679D4A34E9CA8DFA650E2B04E02C1ACA1@onstor-exch02.onstor.net>
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Thread-Topic: Performance Issue - burst of writes
Thread-Index: Acdhr5g5gmS0gQ6bT+O349R+kp5mIA==
From: "Rex Yuan" <rex.yuan@onstor.com>
To: "dl-cstech" <dl-cstech@onstor.com>

This is a multi-part message in MIME format.

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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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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Dus-ascii">
<META content=3D"MSHTML 6.00.2900.3020" name=3DGENERATOR></HEAD>
<BODY>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>Hello =
all,=20
</FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial=20
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>I'm =
working with a=20
customer who is seeing performance issue.</FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial=20
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>The =
customer has a=20
cluster of two 2240s and everything is working fine.</FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial =
size=3D2>Recently, the=20
customer swapped out one of the 2240s and replaced it with a=20
2280.</FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial=20
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>On the =
2280, the=20
customer is seeing performance issue.&nbsp; Asked the customer to=20
</FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>use =
different linux=20
clients to read and write to the same nfs share.&nbsp; =
</FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial=20
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>1. =
Asked the=20
customer to perform read test on the filer. <BR>collected stats "evm =
show stats=20
-r" and "port show loadstats -i 2"<BR>From the stats, read operation =
seem to be=20
normal <BR><BR>2. Asked the customer to perform write test on the filer=20
<BR>collected stats "evm show stats -r" and "port show loadstats -i 2" =
<BR>From=20
"port show loadstats -i 2", we see the write operation writes for 10 =
seconds=20
then </FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>pauses =
for 20=20
seconds.&nbsp;This behavior continues throughout the entire write =
operation.=20
<BR><BR>3. Asked the customer to perform read and write test at the same =
time.=20
<BR>collected stats "evm show stats -r" and "port show loadstats -i 2" =
<BR>From=20
"port show loadstats -i 2", we see the same write then pause behavior.=20
</FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial=20
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>We =
swapped out the=20
2280 with the original 2240 and everything worked =
fine.</FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial=20
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>What =
would cause=20
such "burst of write" behavior?&nbsp;&nbsp;</FONT></SPAN></DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial=20
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D814551218-08032007><FONT face=3DArial size=3D2>Thank =
you in=20
advance.</FONT></SPAN></DIV>
<DIV>&nbsp;</DIV>
<DIV align=3Dleft><FONT face=3DArial size=3D2>Rex Yuan</FONT></DIV>
<DIV align=3Dleft><FONT face=3DArial size=3D2>ONStor=20
Support</FONT></DIV></BODY></HTML>

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