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DS8300 Capacity

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NCWJ

MIS
Jan 30, 2008
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Hi guys, I'm new to storage administration on the DS8300. We have the following. 96 73g drives, 7008g of raw storage, 4912g of available storage and 3966g of used storage and 946g of available raw storage. We have 12 arrays, eight 6+P+S and four 7+P. My question is if we only have 946g of available raw storage which is the available minus the used, does this mean we have about 2000g still available for configuration ?
 
That available raw storage is the amount of licensed raw storage not yet used. DS8k licenses are procured in 5TB and 1TB chunks (minimum is 5TB I believe).

946GB available means you can probably expand with another 16-pack of 73GB drives without having to buy additional license.

But you also may want to see if you still have arraysite's not yet configured into arrays and then raid ranks and allocated to extentpools.

Tip: count all arrays: for 96 disks, you should have 12 arrays (8 disks per array: Raid5: 6+S+P or 7+P or Raid10: 3+3+2S or 4+4). If you have less than 12 arrays, you still have unused storage in the DS8k.

All this without any calculations done. You'd have to go through a config session to know where you're at. (IBMer or BP can do that for you).


HTH,

p5wizard
 
We're running out of space. Someone has suggested instead of using 6+P+S we use 7+P it would buy us more space. Which is the best practice though ?
 
That I'm afraid you can't do in a DS8k. When configuring ranks into RAID-5 groups, the system decides for itself if it has to create them in 7+P or 6+P+S.

You want to have those spares because the system allocates one of them in place of a failed disks to recreate the RAIDgroup that is affected by the failure.

The more types/speeds(rpms)/sizes of disks you have in the DS8k, the more spares the system needs and allocates by creating 6+P+S RAID groups first and then when it has enough, 7+P RAID groups.

The DS8k does that for each device adapter pair it has running. So when you add an expansion cabinet, this 6+P+S/7+P allocation starts all over again, because those disks are connected to a separate device adapter pair.

For mirroring groups, it is the same thing. First 3+S/3+S mirrors and then 4/4 mirrors.

So if you're running out of space, you'll have to add more 16-packs of disks and possibly you'll have to add an expansion cabinet...


HTH,

p5wizard
 
NCWJ,
If you need more Disk storage for the DS8300 I can help to supply you with what you need. I am a IBM storage supplier. We can offer IBM certified refurbed upgrades for a fraction of the cost of the new storage. I am also always looking to buy back any DS8100 or DS8300 machines. I can pay you for any of your machines you are looking to deinstall. We also provide full storage services for the deinstall, data erasure, etc. Please contact me if you think we can work together.
 
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