Moving dynamic striped disks

[Nick Payne]

I have a Windows 2003 server using drives on an EMC CX700 SAN. The logical
disk in Windows is formed by using windows disk management to stripe in
software across dynamic disks that are mirrored RAID-1 in hardware. I want
to simulate a server crash by unzoning the disks from the present server and
zoning them to a different Win2003 server. Is it possible to get the new
windows server to recognise the existing data drive that is striped acorss
the disks if the LUNs and disk numbers are exactly the same as on the
original server.

It's easy enough to do with AIX, is it doable with Windows? I hunted around
in Technet for a while but could find nothing on this topic.

Nick

 

[Rick Gouin]

Yes. First you have to make those LUNs available to the new 2003
server. If you are moving striped or mirrored drives, you need to move
all the disks together, and have them all available. Once the
different machine can see all the drives, go into disk manager and
click "Import Foreign Disks".
More info here:
http://www.microsoft.com/resources/.../2003/standard/proddocs/en-us/dm_add_disk.asp

Out of curiousity, why would you do this? Why not just create a
MetaLun on the Clariion that is a stripeset made up of the mirrored
Raid1 drives? This way it would present to the OS as one drive, even
though its a stripeset of mirrored disks, AND it would keep the
overhead off the server itself. Just a thought - let me know if you
need more info.

If that doesn't answer your question, let me know and I'll try to help!

Regards,
Rick Gouin, MCSE

 

[Nick Payne]

Better throughput with striping in software. We did some testing with
Win2000 and Win2003 servers. With Win2000, there was virtually no
performance difference between doing all the striping in hardware or doing
it in software. With Win2003, we got a sevenfold increase in throughput by
doing the striping in software instead of doing it in hardware. I guess the
difference is between having one LUN available for I/O if it's all done in
hardware vs multiple LUNs available if it's done in software.

Nick

 

[Rick Gouin]

That is an interesting thought. So 2003 will parallelize the I/O if it
thinks it has multiple physical disks to access.

Were your gains experienced in reads, writes, or both? Just curious
because I also have a CX700 and 2k3 servers - I might have to try this
out!

Were you able to import those foreign disks? Did that work ok for you?

Regards,
Rick Gouin, MCSE