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AX4-5 Disk Configuration
Hi all,
I'm preparing a configuration for a my customers, I'm a newbe on Ax4 configuration.
I' ll propose this configuration.
4+1 on 300Gb 15K SAS for esx 3.5 VMs in raid 5
7+1 on 400Gb 10K SAS for slowly VMs and RMD mapping ..raid 5
1 400Gb 10k SAS hot spare
What do you think about this configuration?
Another question...
On Clariion cx family the suggested raid 5 disk configuration are : 4+1 , 8+1 , 12+1 . In ax4 family the disk configuration is the same?
thanks
Matteo
I'm preparing a configuration for a my customers, I'm a newbe on Ax4 configuration.
I' ll propose this configuration.
4+1 on 300Gb 15K SAS for esx 3.5 VMs in raid 5
7+1 on 400Gb 10K SAS for slowly VMs and RMD mapping ..raid 5
1 400Gb 10k SAS hot spare
What do you think about this configuration?
Another question...
On Clariion cx family the suggested raid 5 disk configuration are : 4+1 , 8+1 , 12+1 . In ax4 family the disk configuration is the same?
thanks
Matteo
RRR
5.7K Posts
0
November 6th, 2008 13:00
On an AX not the first 5 drives carry the Flare code, only the first 4, so you should reconsider your design and you will be "throwing away" disk space on disk 0_0_4 if you create a 5 disk RAID5 RG. Furthermore: I wouldn't put high performance data on the first 4 drives.
Usually I don't even use the first 4 drives on an AX (or 5 on a CX), but when the customer is not willing to pay extra (since you cannot use the free space on the first drives), you don't have a choice.
DCw5K
1 Message
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December 10th, 2008 09:00
sureshctr
36 Posts
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January 4th, 2009 23:00
You can refer the Vault disk guides to understand the layout better.Though the OS occupies 20% of the disk space alone,it's not a best practice to use those disks for data.
Hope you got it!
Anonymous
274.2K Posts
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January 6th, 2009 23:00
andyxzyk1
44 Posts
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July 14th, 2009 12:00
1. It is true that EMC recommend to keep IOPs down to 100/drive on the vaults.
2. It is NOT true they recommend not to put any customer data on there.
3. Performance penalty only occurs during a possible rebuild (usual RAID penalty for rebuilds) plus the write cache gets disabled hence a further write penalty.
Write cache penalty can be alleviated by disabling HA vault option but then you run the risk that if something happens you may lose write IOs because they are no longer going through cache where they're protected by the SPS.
4. If my memory serves me right with the latest FLARE you lose about 33GB on each vault drive which needs to be taken into account if combined with larger drives in a RAID group since the RAID group will get created based on the smallest drive size.
The vault drives mostly get used during boot-up and to protect write cache in case of problems. From tests we've run we did not see much performance difference between the vaults and the rest of the drives (obviously of the same type/size).
Earlier FLARE code suffered more from this phenomenan and this 'perception' propogated as the Clarion matured, however current FLARE is much more efficient at using these drives and minimizing any performance penalties.
This is my current understanding, if anyone knows anything different I am always open to learning new things.