2011-11-02 11:04 AM
I am needing some help with figuring out what the optimal RAID size would be for adding 56 133Gb FC disks to my current system. I am using an FAS3040 with Data OnTap vs. 7.3.4. I will be configuring for RAID DP and would like to only allot 4 disks for parity out of the 56 total disks. All help is greatly appreciated.
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2011-11-02 11:10 AM
With 32-bit aggregates, you can have 141 total disks (data+parity) and a max of 123 data disks with 144GB drives. With 56 disks, I would consider 2 spares with 54 disks and go with 3 raid groups of 18 [3*(16D+2P)]... that keeps raid groups the same size for better performance and meets the requirements for rapid raid recovery with 2 spares which is plenty for 56 drives as long as you have a support contract or extra disks to swap out when they fail.
If you want only 2 raid groups (4 parity drives) you could go with 2 raid groups of 27 [2*(25D+2P)] but I wouldn't go with raid groups that big (the max is 28 with RAID_DP but odds of failure, rebuild time, etc. not a great idea to go that big).
2011-11-02 11:18 AM
My only issue is that these disks went out of warranty earlier this year. My boss wants me to continue to use them but make sure I have up to date Full and Incremental backups of the data in the event of loss. Which is why I was thinking of having 4 parity disks. Knowing now that there is no warranty would you still think 3 raid groups of 18 is fine?