Assuming I have two nodes HA cluster, each node has an aggregate, and also owns a spare disk, if one spare is being already used, and the second disk failed, can the other spare owned by the other node be automatically picked up for 2nd failure?
I think the answer is yes, but just to make sure with you.
So, you can use the spare disk from the other node. To do that, you will need to assign ownership of the spare disk from NodeB to Node A. This also means that there are no spares disks available for NodeB.
Here it comes a touger question, I didn't intend to ask you at beignning.
I have two AFF nodes in the cluster, and each node already has 28 ssd disks(3.8TB) filling up the first raid-group in the aggr. Now, if I am adding one more ssd shelf with 24 disks. I can do: 1. add 12 disks to form 2nd raid-group, in the existing aggr on each node, 4 disks will be used for parity..
2. form a new aggr/raid-group with 24 disks on one of two nodes, 2 disks will be used for parity.
No extra spares needed, because each node already has its own spare. Option 2 will have about 6 TB more than opetion 1.
Which opiton would you go with? I probably would go option 1, only becuase it will balance well, althrough it would loss about 6TB usable space. The only thing is if there are any benifits to leave the entire shelf belong to an aggr, not split it to two different aggrs?
With SSDs, raidgroup sizing doesn't have to be as uniform as spinning disk, due to latency differences between raidgroups due to different utilization not being as much of an issue. We still want to avoid "hot spindles", but it's a much higher threshhold
Is controller CPU utilization about equal? if so - add to both
Is one controller more heavily utilized? if so - add to the other
Is there a uniform need for more capacity? if so - add to both
Is there a targetted need for more capacity? if so - add to that controller.
Do you anticipate budget in the remaining lifespan of the system for another expansion? If so, add to one this time, the other next time. Even if not, consider only adding to one this time to get best capacity.
Just to make sure, is it true that we only need one spare on each node, and no need to add any more even after add this new shelf? Including this new shelf, we will have total of 3 and half shelve for this AFF HA pair.
What would be the ratio of how many ssd shares should be configured for how many total of SSD's or shelves?
It's up to every admin to decide what they're comfortable with - my usual recommendation is 1+1% per type per controller - so if you have 24 disks, or 72 - 2 spares per controllers are fine, at 144 drives, you probably want 3. But if you're physically close enough to the system to replace drives as soon as they come in, maybe you're happy with 1 per controller, or if it takes 4 weeks to get replacement drives to it because it's on a ship in the middle of the ocean, maybe you want 6.
In ADP and root-data partition case, a hot spare could be a hot spare disk partition, and counted as one of how many spares should be defined. Correct?
Though we can use a disk as a hot spare for partitioned disk to replace the partitioned disk should one of partition gets failed. But, usually, for partitioned disk, we should use root or data partiion for the hot spare, and for unpartitioned data disk, we should use a unpartitioned disk for the hot spare.Correct?
Yes - in theory only one partition may fail, but in practice it's probably both/all partitions on a disk that fail. After that, the root partition may be rebuilt onto different disks to the data partitions.
On systems with mixed partitioning, a partitioned drive will not automatically take the place of an unpartitioned drive if it fails.