From: Callum Hughes (Callum.Hughes@sis.securicor.co.uk)
Date: Fri May 03 2002 - 06:31:47 EDT
Hi everyone
Something that is troubling me about some new configurations we're
implementing concerns Veritas Volume Manager and Sun T3 Storage arrays.
We have a two node cluster attached to which we have two basic entry level
T3 disk arrays. Within each of the disk arrays, we have 8 disks in a RAID 5
configuration with one hot spare. Volume Manager then controls each "mirror"
and sees two LUNS, one on each array.
My concern is this: When Volume Manager sees a disk failure on a disk it's
controlling, it usually drops it from the configuration. If this is the
case, even with RAID 5 and hot a spare, one disk failure in the LUN on the
T3 will mean that VM will drop half of the mirror. The T3 will chug away
nicely rebuilding that half of the mirror with it's hot spare now brought
into the arrangement and that's fine. But then, the only way I can think of
replacing a failed disk (or in this case LUN) on VM is to initialise it. And
we all know what happens when you initialise a disk with VM, thus making the
RAID 5 configuration pointless.
Now, can anyone either confirm or refute this scenario? Is there someway
that I don't know about within the T3/VM arrangement that prevents VM from
seeing a failed disk on a T3, within a LUN, within a RAID 5 configuration
as a problem? Management are saying "Of course this won't happen! That's why
we have RAID 5!" but my Volume Manager experience tells me that once VM sees
a problem with a disk it drops it. This may not be true with LUNS but I
*assume* that Veritas controls a LUN in the same way that it controls a
disk.
Callum A. Hughes
Unix Systems Engineer
e: callum.hughes@sis.securicor.co.uk
**********************************************************************
The information contained in this e-mail message is intended
only for the individuals named above. If you are not the
intended recipient, you should be aware that any
dissemination, distribution, forwarding or other duplication
of this communication is strictly prohibited. The views
expressed in this e-mail are those of the individual author
and not necessarily those of
Securicor Information Systems Limited.
Prior to taking any action based upon this e-mail message
you should seek appropriate confirmation of its authenticity.
If you have received this e-mail in error, please immediately
notify the sender by using the e-mail reply facility.
**********************************************************************
_____________________________________________________________________
This message has been checked for all known viruses on behalf of Securicor Information Systems by the MessageLabs. For further information visit http://www.messagelabs.com or Email: mailsweeper.info@sis.securicor.co.uk
_______________________________________________
sunmanagers mailing list
sunmanagers@sunmanagers.org
http://www.sunmanagers.org/mailman/listinfo/sunmanagers
This archive was generated by hypermail 2.1.7 : Wed Apr 09 2008 - 23:24:17 EDT