RE: OS400 DATA MIGRATION -- MIDRANGE-L

Well, first of all, you can't add 8 gig drives to a RAID set composed of 4 gig drives because all drives in a RAID set must be composed of drives of the same size and type. You can create a new RAID set with the new arms but they cannot be part of the existing set composed of 4 gig drives. Presumably, your existing IOP will support two RAID sets.

Someone else will post the details but, in general, you can indicate that drives 9 and 10 in the existing RAID set are being withdrawn and that you want the data that they current contain to be spread over drives 1 through 8 in the RAID set. STRSST then work with disk.

Be advised, if you have any periods of very heavy disk insert, update, or delete and if there is only one disk IOP for all your RAID disk then you run the risk of overloading the disk IOP that is supporting you RAID sets with RAID computations. If your database is journaled, there is a "doubling" effect - the effect of each insert/update/delete causes a write to the database and another write to the journal. Since the database and journals are in RAID sets, each write (journal and database) causes two reads and two writes - the reads overlap and the writes overlap. All of this IO can be very hard on your disk subsystem.

Using the normal defaults, your current system has 48 gb with 40 usable and 36.8 gb of data and programs and so forth. When you are done, you will have a total of 108 gb with 87.42 gb of usable space therefore your projected disk space utilization will be 42 percent. You should rebalance that data across all the disk arms. If DSKBAL isn't available, you will need to unload then reload in order to balance the storage. If you don't rebalance, you will see very heavy utilization of the new (empty) drives when objects are created.

Richard Jackson
mailto:richardjackson@richardjackson.net
http://www.richardjacksonltd.com
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-----Original Message-----
From: owner-midrange-l@midrange.com [mailto:owner-midrange-l@midrange.com]On Behalf Of oludare
Sent: Monday, October 09, 2000 9:35 AM
To: AS/400 Midrange Usergroup
Cc: Michael Thomas
Subject: OS400 DATA MIGRATION

Hi guys,

I'm on V3R7M0 and running about 92% DASD usage.

What do I need to know to perform DATA MIGRATION. I need to perform DATA MIGRATION before IBM CE come in for hardware upgrade. I'm planning DASD upgrade and need to remove 2 X 4gig old drive from a RAID set then add

7 X 8.58gig more to the raid set (Raid has 16 arms). I need to get all data on 2 old drive spread out on the remaining

8 X 4gig before hardware upgrade by CE. The 2 X 4gig DASD will be added to bottom mirrored 2 X 4gig. At the end I should have 8gig Mirrored and a little above 92Gig on the Raided top 15 drives.

Thanks for your input.

Dare