DS4500 LUN

[THEaix]

I have this in the IBM DISK RAID forum as well, but doesn't seem to get the traffic as this forum and since it's attached to an AIX.....

I have a DS4500 Disk system with one(1) 710 drive tray (mgmt won't by a second tray)with 14 279GB drives attached to a IBM P550. I'll have three(3) databases running on it (1 Db2 and 2 oracle 10g). This will be a DR site with actually only one of the DB's active everyday, unless we have a DR issue. The DB space needed is about 1TB for all of them.

I am thinking that 1 raid5 of 12 disks + 2 hotspares will get the best possible performance with some redundancy. The single LUN would be 2.5 TB. I'mm looking for some advice as to whether this is a viable solution or if splitting out the drives into smaller LUN's with less disks would be better or with them all being on 0ne drive tray if it really makes a whole lot of difference.

 

[itsp1965]

Since you will be installing databases, you may want to discuss with your DBA(s) what growth will you be expecting
Also, depending on how the databases will be configured, you may want to consider setting up some LUNs with RAID-10 in order to support transaction logs (again talk to your DBAs)

 

[khalidaaa]

If you have so many disk I/O then it is better to split the the drives into smaller LUNs because this will reduce the disk hit for each compared of having one disk contating every thing.

Regards,
Khalid

 

[THEaix]

I know this horse has been beat a number of times, BUT wouldn't it be better to have data, indexes, redo, logs split accross 12 spindles than having data on a couple, indexes on a couple etc etc.?

 

[khalidaaa]

Well, we had this design of separating the data, indexes and redo logs but as an advice from the IBM consultant, who came to help configure our P5 570 machine, that SAN will handle the behind-the-seen transactions and it doesn't matter where to put which (if i understood correctly)!

Now we have a standard size LUNs of 13.5GB (by splitting the 73GB into 10 LUNs) and we put our DBs regardless of the indexes or redo logs placement.

Again, maybe our design is for small DBs so you have to test the best design for your organization.

Regards,
Khalid

 

[chgwhat]

There is a best practice guide for the 4500, that specifies best number of spindles, that is what I would follow. I would look at 2 raid5 setup. You want to set it up to meet the db requirements, ie: read/write size, and iops required. Which require a lot more info. If you have these db currently on site do some monitoring, you don't want the DR site to be a lot slower the the main site. My target would be to match or beat current performance.


Tony ... aka chgwhat

When in doubt,,, Power out...