The system is running DataONtap 8.1.4P8 7-Mode, on a FAS3240
I need to add a spare disk to an aggregate, this aggregates is the only aggregates with 3TB SAS disks, I have other aggregates with 600GB SAS and 1 TB SATA disks.
I want to ensure physically adding the drive will not assign the disk as data drive into the 3TB aggregate ( called aggr3_sata_svault1 ) or any other aggregate as I want it to be a spare.
Currently disk auto assign is enable, should I turn this of first?
The aggregate in question as 5 data disks and two parity,(shown in the sysconfig -r output below) however the aggr options command shows the number of disks in the raid group as 14, should I set this to a lower number ie 7 to ensure the disk is not added as a data drive, is shrinking the raid size even possible/supported.
You don't add space disks to aggregates. Aggrs consist only of data and parity drives. Spaces exist in the spares pool and will be called on IF a data/parity drive fails. As for the RAID size value. Yes you can change that if you want, however OnTap will not pull a spare disk into the aggregate, only a human will do that. In other words, OnTap will not grow the aggregate just because it has spares and the RAID size is greater than the allocated drive.
disk.auto_assign will assign an unknown disk to a file server. Each disk is owned by one of the heads in an HA pair and this just means that when an unknown disk is inserted it will be automatically assigned to one of the controller. It does not mean that an unused (spare) disk will be automatically added to an aggregate.
If am understanding your response correctly when I add the new disk it will be automatically added to a pool consisting of spares, thus achieving my goal of just getting an extra spare into the system.
Just to clarify on the disk.auto_assign, if a drive fails it will always use a spare regardless of the disk.auto_assign setting. If the disk.auto_assign is off and a replacement for a failed drive is inserted it will stay un-owned until manually assigned and as the drive is a replacement for a failed drive that has been already added into the aggregate the replacement drive will appear as spare.
"when I add the new disk it will be automatically added to a pool consisting of spares"
When you add a new disk? Meaning if you add a shelf or add disks to a partial filled shelf, then yes.
"if a drive fails it will always use a spare regardless of the disk.auto_assign setting"
"If the disk.auto_assign is off and a replacement for a failed drive is inserted it will stay un-owned"
Yes, assuming we're talking about software based disk ownership. I think if you're working under hardware based ownership then this has no affect and the drive will get auto assigned to the controller that owns the shelf.
"until manually assigned and as the drive is a replacement for a failed drive that has been already added into the aggregate the replacement drive will appear as spare."
Yes, that's correct. BTW you can see unknowned drives via 'disk show -n'
I recently physically inserted the drive into an empty bay slot, and the drive appeared as an un-owned disk, I then run the command disk assign and it made the drive spare. Thank you for reponses, they were spot on.