Disk Configuration

[Jorge Mel]

I am installing a new HPUX server with MSA30 disk storage. I running Oracle database. My questions regards how to carve the disk for file system usage for best performance.

I need 438GB of useable space

My options:
10 73GB dsk for RAID5 three LUNS and 1 disk hot spare; each LUN a raid 5 of three disk for 146GB useable space.

9 73GB dsk for RAID5 two luns and 1 disk host spare; each LUN a raid 5 of 4 disk for 219GB useable space.

OR insert 146GB and make one LUN of raid 5 with 4 disk for 438 useable space

What is the best choice for IO performance?

[Steven E. Protter · Accepted solution]

Shalom,

The answer is of course "it depends" (A. Clay's quote).

It depends in this case on what you need the storage for. If you need 438 GB for a write intensive database then none of these solutions will work.

If you don't have a lot of writing going on, you generally, all things being equal will get better performance spreading your data across the most disks. That increases the chance that a disk head is where its needed when its needed.

Another factor you must consider is seek time is usually less on smaller disks.

Oracle intself recommends raid 1 or raid 10 for data, index and redo logs. None of these scenarios really deals with that.

Seems the first two solutions will adhere to the priniciples I've already laid out, you'd have to actually run tests to be certain.

http://www.hpux.ws/system.perf.sh

SEP

[Jorge Mel]

Thank you for your information. Your feedback helps my decision making. What I did not say was that I am moving the Oracle (SAP)application from K580, AutoRaid 12h to a RP3440, MSA 30. The 12h AutoRaid is configured as RAID 10, so my inclination is to configure the MSA 30 is a RAID 10 config, feedback.

[A. Clay Stephenson]

Your AutoRAID is configured at whatever level it feels like at the moment; that's why it's called AutoRAID although if you always keep the configured (as LUN's) space below 50%, it will remain at RAID level 1/0.

You can never go wrong by selecting 1/0; it's always going to be a good choice for performance --- at the expense of less efficient storage utilization. With heavily cache-centric arrays, it is often more important to get the data to the array over as many independent channels as possible than it is to worry about the disk layout itself. Just as using RAID 1/0 will never hurt, spreading the I/O over as many separate controllers as possible will never hurt but neither of these techniques makes as much difference as it once did because bandwidths are higher and caches are bigger.

[Sandman!]

Of course the best answer again would be quoting Clay..."it depends". The RAID level should mostly be determined by application usage patterns. However, if you want to reduce wasted disk space then RAID 5 should be preferred over RAID 10. On the other hand if the utmost availability and fault tolerance is the goal then RAID 10 should be your choice.

~hope it helps

[Jorge Mel]

All information provided help in my decision making.