I wonder if I can canvas any opinions or thoughts (good or bad) on SAN attaching a SUN V880/490 to an EMC Clarion SAN?
At the moment the 880 is using 12 internal FC-AL disks as a db server and seems to be doing a pretty good job. It is not I/O, CPU or Memory constrained and the internal disks are mirrored in a RAID 0+1 configuration.
I have 2 choices to make as we intend to increase the number of db's running on the machine(s) - these options are:
1 - To directely attach the servers to the EMC SAN with FC HBA's.
2 - To purchase StoredgeTek SCSI shelves and use SVM to manage the disks (FCAL is overkill to be honest).
I know there are all sorts of ways the SAN can stripe and chop up the disks to allow for RAID 5 etc and that SVM will make a pretty good job of doing the same on the SCSI shelves.
However I do not know if there are any significant technical advantages/disadvantages for either of these two methods.
Does anyone have any thoughts on this?
My own concerns are the reliability of the connection to the SAN as apposed to directly attaching the SCSI shelves. I feel keeping the SUN kit self-contained may be preferable in the long run.
Irrespective of the storage used it is usually much easier if you use host based mirroring, as this allows you to do backups using the detached mirror of a raid 1, and apply the correct logic for making sure the backup is clean, for example to quiece a database while the mirror is being detached.
RAID5 in hardware would protect you from failure of a disk during the time the mirror is deatached. Personally I find attached fiber storage much easier to work with than SCSI becasue there is no need for example to configure multiple initiators and things like that, also it much easier to configure a multi-pathed configuration.
You could consider doing a mixture of the two, something like 3511 JBODs, with SATA disks and attached them using fiber HBAs, you wouldn't have the RAID 5, but you would have the extra low cost storage. This would also offer you the possibility of moving onto the SAN at a later stage, with much less work.
THis is a question of intent and expected future growth of not only the app but the business you are supporting. If there is a high growth potential of the business with a requirement for hig performance then I would invest in a EMC and throw in a Mcdata Fiber switch. If this is the case, then a netbackup solution should natually follow given its benefits of backing up and enterprise environment (hot backups, incremental backups, etc.).
This configuration will lend its itself much better to adding systems,clustering for ha, application clustering, performance, etc.
Your concern of reliability is addressed with dual paths to the EMC (preferibly on different PCI cards) using DMP on the Host.