In the past, servers I've put together have all had 8 or fewer disks, so I've not had to give the storage controller much thought - a standard controller like the P440ar (my experience is with HP) that supports up to 8 disks is sufficient.
The server I'm currently spec'ing up will likely have between 10 and 12 SFF disks, meaning the usual standard P440ar will not be sufficient. To support >8 disks, it seems I have a couple of options:
- Stick with the P440 and add a SAS expander card
- Switch the controller to something like a P840 that supports up to 16 disks without a SAS expander card
Therefore, I've been trying to understands the pros/cons of each approach.
I appreciate that you have no option but to use a SAS expander if you want to create a RAID array that spans more disks than the controller itself supports. Assuming that's not the case, what are the pros/cons/differences between:
- Smaller controller + expander
- Larger controller
(where 'smaller' is a controller that doesn't support the required number of drives without an expander, and 'larger' is a controller that does)
... and when/why would one choose one option over the other?