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SridharAdari
5 Posts
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3422
June 1st, 2012 14:00
How does a pool work
Hi All,
We have a VNX storage frame in which we have 240 SAS drives and its a Block storage.
Its a single disk type and there is no FAST CACHE/tiering.
Can i proceed with pool creation ?
If yes, can we create a pool with 240 disks ? Which raid ?
If we create a storage pool of Raid 6 with 80 drives and if i create a lun of 200GB.
Will this 200GB will created from all the 80 disks or will it create from 8 disks only, as while creating storage pool it says recommended is multiples of 8.
Also i noticed that if i create a R6 storage pool with 80 disks then it gave the usable space as the size of 60 drives and 20 drives it took for parity creation.
So does this mean that whenever we create a lun will it take from 8 disks and in that 2 will be for parity ?
Please update if there is any document which can explain better about the storage pool and raid group.
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Posted June 5th, 2012 00:00
If I'm correct the new Pool setup allows for having multiple RAID levels inside pools, right? So RAID6 for NL-SAS, RAID5 for SAS and RAID10 for EFD, right? I'm really looking forward to this new feature since having everything in my pools as RAID6 really bugs me
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I also think I heard mentioning that the 1GB chunks will now be replaced with much smaller chinks. I think it's 768kB, so this would make a much better use of the expensive EFD drives in your pool!
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Posted June 5th, 2012 13:00
Multiple RAID levels per pool - yes
Code isn't released yet
Slices are 1 GB as before
768k is VMAX which is a different beast
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Posted June 9th, 2012 08:00
As you mentioned the 1GB chunks. Just FYI, I recommand customers, and EMC engineering team focus on PPLUN size and relatives enhancements. And hoefully you all understand why.
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Posted June 9th, 2012 13:00
what is PPLUN ?
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Posted June 9th, 2012 21:00
Hi All,
Thanks for the responses.
I heard that the pool with Raid 5 will have issues in rebuilding the data in the event of disk failure.
Which is the better configuration.
In some doc i found that receating pool with more number of disks will be better ?
Is there any limit for disk count?
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Posted June 11th, 2012 03:00
Ah, VMAX... I thought I was mixing up 2 FAST implementations, especially now I'm working on VMAX again as well
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Well, if it's still 1GB on VNX my next RFE (Request for Enhancement) would be to implement smaller chuncks on VNX as well.
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Posted June 11th, 2012 03:00
Another RFE (if not already in the new code) would be a rebalance button / feature, so every LUN can be rebalanced accross all spindels in a pool (per tier).
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Posted June 11th, 2012 04:00
RRR wrote:
Another RFE (if not already in the new code) would be a rebalance button / feature, so every LUN can be rebalanced accross all spindels in a pool (per tier).
new code will have the rebalance feature, did you go to EMC World this year ?
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Posted June 11th, 2012 05:00
Yes, in the new code rebalance will automatically happen when you add new drives to a pool and it will also rebalance within a disk tier during the normal FAST VP relocation
Rainer_EMC
6 Operator
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8645 Posts
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Posted June 4th, 2012 08:00
Sure – you can use pools without a FAST VP license
For RAID levels you have a choice of RAID 1, 5 or 6
The VNX will then create private (hidden) raidgroups with the preferred multiplier.
A data LUN will be spread over multiple internal raidgroups in 1GB slices
Some details are in the FAST VP and VP white papers
http://powerlink.emc.com/km/live1/en_US/Offering_Technical/White_Paper/h8058-fast-vp-unified-storage-wp.pdf
http://powerlink.emc.com/km/live1/en_US/Offering_Technical/White_Paper/h8222-vnx-virtual-provisioning-wp.pdf
The exact workings and distribution isn’t published externally AFAIK
Note that pools and FAST VP are going to be enhanced in the next major release.
For details you need to talk to your local EMC contact since it is still considered roadmap.
Rainer