Summary: break RAID5 into JBODs

From: Li Zhao <Li_Zhao_at_ismbc.com>
Date: Tue, 29 Aug 2000 10:13:32 -0700

Thanks to alan_at_nabeth.cxo.dec.com. His answer is very helpful. Here it followed:

     re: reconfigure from scratch.

     Probably. RAID-5 distributes data evenly among the disks
     being used. JBOD puts all the data on a single disk.

     re: How long.

     You'll have to backup all the data. Reconfigure, create
     new file systems and restore. The time to reconfigure
     will be minor compared to the data movement.

     Each RAID Array 200 only presents 8 logical units back
     to the host operating system. If you're using more
     than two shelves worth of disks, you have more than 8
     disks to be presented. From the description of having
     two controllers that 16 logical units, but 35 disks.
     You can't get there with just JBOD. Striping will let
     you combine disks and get the full available capacity.


I think I will have to go on his suggestion: stripping instead of JBOD. Thanks
again Alan.


Original question:
Dear managers,
Due to capacity limitation, I need to break my RAID5 into JBOD. I have RAID
Array 200 Subsystem on my Alpha 4100 running Digital Unix 4.0D. I have 2 XCR
controllers, one has 3 RAID 5 on it which consists 5x4.3G, 5x4.3G and 7X4.3G
disks accordingly; the other has 5 RAID5 which consists of 4X9G, 4X9G, 4X9G,
3X9G and 3X9G disks.
If I want to break those RAID5, my questions are:
1. Do I need to configure the JBODS from the scratch, or is there any short cut
that I could just turn RAID 5 into JBODs?
2. How long will the whole precudure take?

Thanks in advance for your help. Will summarize.

Li
Received on Tue Aug 29 2000 - 17:13:39 NZST

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