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Didierv-ca
7 Posts
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December 20th, 2012 02:00
On a VMAX, where is this information : Disk array RAID stripe size
Hello,
Our Exchange team ask this question : what is the Disk array RAID stripe size (KB) on our VMAX.
They have found this Exchange information :
Supported RAID types for the Exchange 2010 Mailbox server role
RAID type |
Description |
Stand-alone: supported or best practice |
Disk array RAID stripe size (KB) |
The stripe size is the per disk unit of data distribution within a RAID set. Stripe size is also referred to as block size. |
Best practice: 256 KB or greater. Follow storage vendor best practices. |
So we use thin provisionning. 3 Thin Pool
-1 TP FC10K, type RAID1
-1 TP FC10K type Raid 6 (6+2)
-1 TP Sata type Raid 6 (6+2)
We use Meta concatenated for the majority of the luns for this purpose.
So, can somebody help me : Where i can find this information ?
Best regards, Didier.
1659
0
Posted December 20th, 2012 03:00
I think you want to know the stripe size of the Raid in VMAX? Its 128 KB (or 2 tracks)
The default stripe size for Striped Meta is 1920 blocks of 512 byte each.
regards,
Saurabh Rohilla
1659
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Posted December 20th, 2012 03:00
◆ 1 cylinder in Enginuity 5671 and earlier = 960 512-byte blocks = 480 KB
◆ 1 cylinder in Enginuity 5771 and higher = 1920 512-byte blocks = 960 KB
Regards,
Periyakaruppan N (Peri),
1659
1
Posted December 20th, 2012 07:00
Many responses here are about the meta stripe size. For a long time the meta stripe has not been adjustable. When it was adjustable it was always in increments of cylinders. You should assume that this is not adjustable unless you have a very old Symm and SE version.
The RAID stripe size on DMX and VMAX 20k are all 256K. For the 40K and the new 10K it is 128K for 7+1 and RAID6. 3+1 is still 256k. It is not adjustable.
The VP stripe is 768k across the TDATs in a VP environment. This is also not adjustable.
1659
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Posted December 20th, 2012 08:00
Thanks Quincy, good information
1659
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Posted December 20th, 2012 08:00
I'm not sure where you got that table you posted from, but it is incorrect. The DMX1-4 all have 4 tracks for the RAID stripe per disk. The DMX1-2 have a 32k track and DMX3 and above all have 64k tracks. There has been a recent change on the VMAX 40K and the new VMAX 10K where some RAID options went from 4 tracks to 2 tracks to better line up with the VP stripe.
Also I didn't mention that since the meta stripe was made a fixed size, it has always been 960k. On DMX1-2 that was 2 cylinders, and on DMX3 and above it was 1 cylinder since the track size doubled.
1659
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Posted December 20th, 2012 08:00
Thanks Quincy, that table is from EMC's whitepaper
EMC Symmetrix with Microsoft Windows Server 2003 and Server 2008/
regards,
Saurabh Rohilla
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Posted December 20th, 2012 09:00
I contacted the author of that paper, and this will be corrected in future versions. The table will be removed.
1659
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Posted November 9th, 2016 00:00
So how will data actually be written in the end? I assume FAST VP chunks have priority over the stripe size, but assumption is the mother of all... you know.
Take a look at this discussion: Re: To stripe or not to stripe?
Archuperi721
110 Posts
1659
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Posted December 20th, 2012 02:00
The detailed output of symmetrix device will give you the stripe size information.
Symmetrix stripe size is not at 256 KB. Here, everything is calculated based on the cylinder.
e.g.
Meta Configuration : Striped
Meta Stripe Size : 960k (1 Cylinders)
Meta Device Members (4) :
Symdev –sid xxxx show xxxx
Or symdev –sid xxxx list -meta
Regards,
Periyakaruppan N (Peri),