Entry-level FAS systems (with HDDs) will only perform ADP on the internal/embedded drives.
AFF systems will use ADP on up to 48 SSDs across multiple shelves. However, for AFF-A220/A220, you will typically see ADP on the 24 internal SSDs only because NetApp Mfg. initializes the system without any add-on storage.
12-drive entry-level FAS systems (FAS2520, 2620, 2720) with HDD sizes that require RAID-TEC need to be explicitly set RAID-TEC to "false" for internal drive ADP (i.e. LOADER> setenv bootarg.raid.allow-raid-tec? false) to ensure that ADP will use 3d+2p+1s P1 partitions for each node. Important: Once you have initialized the system, set this bootarg back to true so that any additional large-HDD RG's use TEC for optimal protection.
As you noted, if you expand a RG with partitions, spare whole disks will be automatically partitioned. That said, you would avoid the wasted P1 partition "tax" if you simply created a new RG with your external shelf drives as whole disks.
3. As you noted, if you expand a RG with partitions, spare whole disks will be automatically partitioned. That said, you would avoid the wasted P1 partition "tax" if you simply created a new RG with your external shelf drives as whole disks.
Not always the best in this case. Why? If I have 11 or 12 partitioned disks (using RAID-TEC), This should be something like 7d+3p+1s or 8d+3p+1s or 7d+3p+2s. In all cases, RAID-TEC is using 3 parity drives. If I create another Raid Group (of say 8d+3p+1s), it will consume 3 more parity drives (30TB). If I just expand the RAID-group and let the system partition, the worst case you are losing 100GB per disk for the root partition (that would be up to 1200GB which is much better than 30TB).
Exceptions to everything, right? If I have more than an extra shelf, then I would have to consider what happens as I expand and do I plan to add more in the furture. i.e. Do I want the Parity tax now (ad be able to add drives later with no potential partity needed) or just add the parity later?
bin heute in den gleichen Fehler reingelaufen. FAS2720 mit 8 TB SATA Disks. Habe entsprechend den 24 Disk ansatz verfolgt. Hat das Problem gelöst. Die neuen Root Aggregate sind aber dennoch mit 5 Platten Raid_DP angelegt. Ich denke auch an einen Bug. Habe Konsolen-Logs mitgeschnitten. Werde sobald ich etwas Zeit habe einen Case aufmachen dafür. War mit 9.5P8 also aktuelles Release.
I today hit the same issue with a FAS2720 with 8 TB SATA ( 9.5P8 ). Used the 24 disks approach. Solved the issue for me. The new root aggregates are created with raid_dp and using 5 Disks, which is pretty odd, the error messages given. Think about a bug as well. Have logs with me and will try to file case as soon as I find any time for it. Will update accordingly.