Veritas-bu

[Veritas-bu] PCI bus and HBA throughput

2003-04-25 10:42:50
Subject: [Veritas-bu] PCI bus and HBA throughput
From: Eric.Shafto AT drkw DOT com (Shafto, Eric)
Date: Fri, 25 Apr 2003 10:42:50 -0400
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It would be interesting to see whether the situation improves noticeably
with multiple HBAs. Does anyone have some data to share?

-----Original Message-----
From: Paul Winkeler [mailto:pwinkeler AT pbnj-solutions DOT com]
Sent: Friday, April 25, 2003 8:57 AM
To: 'Vijay Korde'
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] PCI bus and HBA throughput


Hi Vijay
 
Here is what we found using two other brands of PCI Bus 2Gbit HBA's in
SunFire 880's going to T9904B's:
1) To a single drive using 2Gbit HBA's, observed peak ~40MByte/sec,
regardless of 33 or 66Mhz bus
2) Writing 3 streams to 3 drives across the same 2Gbit HBA, observed peak
~100MByte/sec regardless of 33 or 66Mhz bus
During all tests source data was fully cached in RAM (machine had 8GByte)
and no other processes running (machine had 8 CPU's)
 
Wconcluded that the bottleneck was likely in the handling of the SAN
protocols across the HBA.  Our basis for this conclusion was this:
- Writing zeroes (/dev/zero) to a single T9940B drive yielded a rate of
69MByte/sec which is basically the upper limit at which StorageTek claims
the drive can take data in; so we know it can go that fast.
- Pushing zeroes to 2 drives simultaneously can be done at an aggregate rate
of ~130MByte/sec on the 66MHz bus, closer to ~120MByte/sec on the 33Mhz bus.
- Going to 3 simultaneous drives with zeroes yields rates of ~138MByte/sec
and 129MByte/sec respectivel for the 66MHz and 33Mhz buses.
In other words, the bus speed gave the 66Mhz bus a slight edge but hardly
worth bothering.  It would be very interesting to see what the results look
like when you use multiple HBA's simultaneously...
 
My advice: don't hang more than 2 drives of a single HBA.
 
PaulW
www.pbnj-solutions.com <http://www.pbnj-solutions.com/>  IT Solutions That
Stick



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<DIV><SPAN class=091074214-25042003><FONT face=Arial color=#0000ff size=2>It 
would be interesting to see whether the situation improves noticeably with 
multiple HBAs. Does anyone have some data to share?</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
  <DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma 
  size=2>-----Original Message-----<BR><B>From:</B> Paul Winkeler 
  [mailto:pwinkeler AT pbnj-solutions DOT com]<BR><B>Sent:</B> Friday, April 
25, 2003 
  8:57 AM<BR><B>To:</B> 'Vijay Korde'<BR><B>Cc:</B> 
  veritas-bu AT mailman.eng.auburn DOT edu<BR><B>Subject:</B> RE: [Veritas-bu] 
PCI bus 
  and HBA throughput<BR><BR></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=426311712-25042003>Hi 
  Vijay</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN 
  class=426311712-25042003></SPAN></FONT>&nbsp;</DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN 
class=426311712-25042003>Here 
  is what we found using two other brands of PCI Bus 2Gbit HBA's in SunFire 
  880's going to T9904B's:</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=426311712-25042003>1) 
  To a single drive using 2Gbit HBA's, observed peak ~40MByte/sec, regardless 
of 
  33 or 66Mhz bus</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=426311712-25042003>2) 
  Writing 3 streams to 3 drives across the same 2Gbit HBA, observed peak 
  ~100MByte/sec regardless of 33 or 66Mhz bus</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN 
  class=426311712-25042003>During all tests source data was fully cached in RAM 
  (machine had 8GByte) and no other processes running (machine had 8 
  CPU's)</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN 
  class=426311712-25042003></SPAN></FONT>&nbsp;</DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN 
  class=426311712-25042003>Wconcluded that the bottleneck was likely in the 
  handling of the SAN protocols across the HBA.&nbsp; Our basis for this 
  conclusion was this:</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=426311712-25042003>- 
  Writing zeroes (/dev/zero) to a single T9940B drive yielded a rate of 
  69MByte/sec which is basically the upper limit at which StorageTek claims the 
  drive can take data in; so we know it can go that fast.</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=426311712-25042003>- 
  Pushing zeroes to&nbsp;2 drives simultaneously can be done at an aggregate 
  rate of ~130MByte/sec on the 66MHz bus, closer to ~120MByte/sec on the 33Mhz 
  bus.</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=426311712-25042003>- 
  Going to 3 simultaneous drives with zeroes yields rates of ~138MByte/sec and 
  129MByte/sec respectivel for the 66MHz and 33Mhz buses.</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=426311712-25042003>In 
  other words, the bus speed gave the 66Mhz bus a slight edge but hardly worth 
  bothering.&nbsp; It would be very interesting to see what the results look 
  like when you use multiple HBA's simultaneously...</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN 
  class=426311712-25042003></SPAN></FONT>&nbsp;</DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=426311712-25042003>My 
  advice: don't hang more than 2 drives of a single HBA.</SPAN></FONT></DIV>
  <DIV><FONT face=Arial color=#0000ff size=2><SPAN 
  class=426311712-25042003></SPAN></FONT>&nbsp;</DIV>
  <DIV align=left><FONT face=Arial size=2>PaulW</FONT></DIV>
  <DIV align=left><FONT face=Arial size=2><A 
  href="http://www.pbnj-solutions.com/";>www.pbnj-solutions.com</A> IT Solutions 
  That Stick</FONT></DIV></BLOCKQUOTE><FONT SIZE=3><BR>
<BR>
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