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Query on FAST VP
Hey Guys,
I have a question related to FAST VP. Although the question looks to be a witless I really wanted to know the answer and hope someone can help me.
Lets say for example, I have two tiers defined in my VMAX , SATA (Raid6- 6+2) and EFD (Raid 5 4+1 ). I have bound the TDEV to SATA pool and applied FAST policy to it. Based on the performance factor, couple of my data chunks/extents moved from SATA to EFD tier.
1. What would be the protection for those data chunks which reside in EFD ? Would it be a Raid 6 or a Raid5 ?
2. If it is going to be a Raid5, isn't it a compromise in data protection method that I was looking for ?
Any help in understanding it will be highly appreciated.!
Thanks..
Prasanna Hegde
KW160
121 Posts
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March 26th, 2017 17:00
1. The extents on EFD would be RAID5 and the extents on SATA would RAID6.
2. No, I wouldn't call it a compromise. EFDs are considerably more reliable than spinning disks and also rebuild from failure much faster. The chances of a double disk failure on EFD is orders of magnitude less than spinning disks.
darrenVCE
25 Posts
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March 27th, 2017 02:00
I think Prasanna is referring to the compromise in data protection between the Raid-5 & Raid-6 disk groups where the extents in Raid-5 can tolerate 1 failure while the extents on Raid-6 can tolerate 2 failures. Answer I think is a trade off between performance and data protection and as an administrator you set it accordingly.
Anonymous
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March 27th, 2017 07:00
Thanks Darren, That is something I was thought but wanted clarification. Cheers!!