I've been asked by a large customer to generate a report in OnCommand Core that will report on the performance-relevant aspects of capacity management within an aggregate - in other words, the % free blocks available for writes within an aggregate (ignoring all reservations, guarantees, or the like - just the free space available to the write allocator). The reason to do this is to be able to proactively order additional storage for an aggregate before write performance is impacted.
Has anyone found a way to monitor this value from within OC?
I think,you are doing wrong calculation. Here, I am going to defined each field and latter I'll calculate space available in aggregate.
Usually, we use "df -A <aggr_name>" and "aggr show_space <aggr_name>" commands to list the aggregate space attributes
df -A <aggr_name> command command will list aggregate capacity, used capacity and available capacity.
Similarly, "aggr show_space <aggr-name>" command display space usage of aggregate in more detail.this command shows the space usage for each flexible volume within an aggregate.
Output of this command display below fields.
Total space: This is total size of aggregate.
Usable space: The capacity available to applications for storing data, this is also call aggregate capacity. you can also check the aggregate capacity space using df -A <aggr-name> command.
WAFL reserve and Snap reserve: WAFL reserve is WAFL metadata and user can not have any control on this.Snap reserve is allocated when user take the snaphot of aggregate.
A-SIS: I am not sure about this field but I think this is space saved in aggregate due to dedupe.
Allocated: The capacity allocated to applications or users for storing data, including effects of thin provisioning. For space guarantee as "volume" (thick provisioning), this field value equal to size of volume and for "none" and "file" space guarantee (thin provisioning), value should be the real data store in volume or volume used space.
Used: This field show application data stored in volume.
"Allocated" and "Used" field's value are with respect to volume.
So, After defining above fields, we can relate the fields as below.
Total space = Usable space + WAFL reserve + Snap reserve
Usable space = Total space - (WAFL reserve + Snap reserve)
thanks for the pointers to the data, I'll looking into scripting a solution until DFM is able to collect these counters natively. Is there something I can do to help get the development in DFM moving (have the customer open an RFE / case / open a BURT)?
Re: How to monitor aggregate free space using OnCommand?