Happy New Year!
For the record.
My colleague (and me as well) were curious so we decided to try what happens if head is just replaced. The sequence was
- shut down MSCS (systems themselves remained booted) - replace filer heads - check LUN properties. LUN went offline first time new head booted and serial numbers did change. Onlined LUNs but nothing more - start up MSCS service
Everything worked just fine; there were no issues with MSCS because of changed serials (at least, visible issues :) )
I am curious now under which conditions preserving serials is really required.
С уважением / With best regards / Mit freundlichen Grüβen
--- Andrey Borzenkov Senior system engineer -----Original Message----- From: Nils Vogels [mailto:bacardicoke@gmail.com] Sent: Wednesday, December 03, 2008 3:56 PM To: Borzenkov, Andrey Cc: toasters@mathworks.com Subject: Re: Upgarding filer head with LUNs and MSCS
Hey Andrey,
On Wed, Dec 3, 2008 at 1:23 PM, Borzenkov, Andrey Andrey.Borzenkov@fujitsu-siemens.com wrote:
Hi,
We are going to upgrade several filers (FAS270 -> FAS3140). They host FCP LUNs and Windows with MSCS connected. Now what I have been told:
MSCS records disks (LUNs) serial numbers; when these serial numbers change, MSCS won't detect and configure its disks. Basically, cluster has to be recreated from scratch
LUN serial number on filer depends on sysid; when sysid changes, LUN serial number will change
as during head upgrade sysid will change so will serial numbers; so MSCS will be very unhappy.
Is the above correct?
Yes, it all is.
Now we'd rather avoid recreating all MSCS configuration. Are there any pitfalls if we save original serial numbers and set them again on new head before MSCS will go online? Will this work or some more tuning is necessary?
No, that's exactly how we do it :-) Use the 'lun serial' command to reset the LUN serial to the value before the head-upgrade and everyone will be happy.
Greets,
Nils