Sparkles1
2 Bronze

How to decide what size hypers for 1Tb disk for thin pool

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We have just had 5 disk groups (consisting of 16 drives) installed in a DMX4.

The Disk Groups consist of 1Tb SATA disks, the remainder of the frame is 300Gb FC disks.

The SATA is to be setup as 60% in a Virtual pool and the remainder for classic provisioning.

The disks are set for RAID 6 (14+2).

Question is what size should the data devices be for the thin pool?

current sizes are 20.48, 29.7, 44.04, and 59.4

Should I stick with these (29.7) or change?

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Quincy561
4 Tellurium

Re: How to decide what size hypers for 1Tb disk for thin pool

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Yes

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Quincy561
4 Tellurium

Re: How to decide what size hypers for 1Tb disk for thin pool

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I think with those size TDATs, you will end up with a lot of them.  I would suggest something that limits the number of TDATs.  I would suggest using as close to 240GB TDATs as you can and utilize all the drive.  This will still end up with around 35 TDAT splits on each drive for this pool.

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Quincy561
4 Tellurium

Re: How to decide what size hypers for 1Tb disk for thin pool

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Sorry, I see this is DMX.  You are limited to about 64gb volumes, so make them as big as you can and hope you don't hit either the hyper per drive or DA target limit.

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Sparkles1
2 Bronze

Re: How to decide what size hypers for 1Tb disk for thin pool

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Thanks for that info, the reason the SATA disks were installed is to accomodate the migration of data from a clariion.

There are LUNs of various sizes allocated accross two Clariions that are to be migrated to the DMX (migration yet to be determined).

I need to claculate how many LUNs are required and by what size and come to an average for sizing.

But wondered if there are any default sizes or tools to calculate the splits?

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Quincy561
4 Tellurium

Re: How to decide what size hypers for 1Tb disk for thin pool

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Since the split (TDAT) size on the disk has no relationship at all to the host lun size, make them as large as you can.  Fewer splits (up to a point) on the disk is better than a bunch.  The ideal splits would be between 8-16.

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Sparkles1
2 Bronze

Re: How to decide what size hypers for 1Tb disk for thin pool

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Have looked at creating larger splits, however get error "the device size specified exceeds maximum allowed"

the limit appears to be 65520 cyl or 60Gb (by CLI or SMC)!

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Quincy561
4 Tellurium

Re: How to decide what size hypers for 1Tb disk for thin pool

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Yes, that is the maximum for DMX.  VMAX goes up to 4x that size.

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Sparkles1
2 Bronze

Re: How to decide what size hypers for 1Tb disk for thin pool

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Therefore I appear to be limited to the max set on the DMX and will need to create them at the 60Gb or so size?

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Quincy561
4 Tellurium

Re: How to decide what size hypers for 1Tb disk for thin pool

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Yes

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