2016-01-06 01:43 AM
Probably quite a simple question on the face of it, but I'm sure there will be a ton of nuance and caveats, but anyway, here goes...
We (will soon) have a pair of fully populated SAS 2246 shelves, no flash pool, but a flash cache cards in the controllers. For info, we are running 7-mode on a pair of 3240 controllers.
Our key criteria is performance, so without going nuts, we aren't so worried about capacity as long as it is quick.
Is their a significant benefit to putting all of these disks into a single aggregate? i.e. 2 or 3 RAID groups.
For example, if I configured it this way and wrote a 20GB file, would this span all RAID groups thus utilizing all spindles.
Any answers or thoughts would be helpful.
Many thanks and happy new year.
2016-01-11 12:14 AM
An aggregate or traditional volume is comprised of one or more RAID groups. A RAID group consists of one or more data disks, across which client data is striped and stored, plus one or two parity disks.
When Data ONTAP's WAFL file system writes data to an aggregate/volume, the data is striped across the data disks in the RAID group(s) and parity is calculated and written to the parity disks. This allows for increased performance as all available disk spindles in the aggregate/volume's RAID group(s) are used.
Also check the Kb 3011896 " How does WAFL and striping distribute data among disks" for more information.
Hope this helps.