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Dear List Users-<br>
<br>
IHAC planning storage layout and is looking for the following MAX_LUNS
size limit on RHEL 3.0 and 4.0. Details are below. Customer database
size is estimated to grow to 5 TB and worries that they will not be
able to present enough devices to the system if used with EMC powerpath
and RHEL 3.0 max_lun limitations. I have advised on using OCFS or ASM
as this is a 10g Database to avoid raw device limitations. In any case,
answer to "max_luns" should appease the customer. Any info will be
appreciated. <br>
<br>
Please copy me on your replies to the group.<br>
<br>
Thanks, <br>
<br>
-sj<br>
<br>
<br>
<br>
<font size="2" face="Courier New"><span
style="font-size: 10pt; font-family: "Courier New";">SERVER SUMMARY:</span></font>
<p class="MsoNormal" style=""><font size="2" face="Courier New"><span
style="font-size: 10pt; font-family: "Courier New";"> <br>
HP Itanium 2<br>
rx4640<br>
HBA INFO... (two different
numbers for the same card)<br>
HP PART #A6826A<br>
QLOGIC Model #Q2342A<br>
Dual Ported HBA (4
ports total, with 2 going to the DMX)</span></font></p>
<br>
<font size="2"><font face="Courier New">RESEARCH DETAIL<br>
<br>
As per EMC PowerPath expert - PowerPath could handle any number of SCSI
devices and that the limitation would be either an OS or an HBA driver
limitation. <br>
<br>
According to RedHat - Modify /etc/modules.conf file which states
"max_luns=". This is normally 128, but can be changed to 256 to
support 256 SCSI devices. Will a higher number for "max_luns" be
supported on RHEL 3 update 4 or RHEL 4? <br>
<br>
QLOGIC - A QLOGIC engineer stated that there can only be 256 devices
seen per HBA which follows the fibre channel standard of 256 devices
per channel. Because we are multipathing, that number would be cut in
half to 128 unique devices per HBA (2 paths per actual LUN device).
Since we have 2 HBA's that we will be using for the DMX, we will have
128 devices per HBA port, or 256 total unique devices. In short, this
means that the OS will be are limiting factor, not the HBA.<br>
<br>
<br>
<br>
</font></font>
<pre class="moz-signature" cols="72">--
_____________________________________
Shankar Jayaganapathy
Partner Solutions Group
Technology Business Unit
Oracle USA Inc.
Phone: 713.553.7942
</pre>
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