What is the max supported number of SATA devices (using cable adapters) on a Dell SAS 6/iR adapter?

What is the max supported number of SATA devices (using cable adapters) on a Dell SAS 6/iR adapter?

- SAS enclosures (No Expander)
- external SAS expander
- SAS switch

SAS (Serial attached SCSI)

Depending on the connector in use the maximum number of SATA drives that can be connected (without active electronics) to a SAS port is 4. If you use an external SAS expander and cascade connections then you can support a very large number of drives (255 SAS / 1020 SATA). Add in a SAS switch and the number goes much higher.

This is really an academic question, though, as the practical number of drives supported on a channel will be limited to a much smaller number as individual servers will tend to scale horizontally with additional SAS ports or up a more traditional SAN or enterprise NAS with a dedicated storage array.

The Wikipedia page on SAS is actually pretty good - http://en.wikipedia.org/wiki/Serial_attached_SCSI . I'd suggest starting there.

I will warn you, though, that a 10-drive RAID-5 array is generally not a good idea - the unrecoverable read error rate of a lot of drives means that you're fairly likely to get yourself into a situation where you loose data even with the redundancy. If you need volumes of that size you're a lot safer using RAID-6 (or even better - RAID 1+0 if you can afford it).

http://en.wikipedia.org/wiki/Serial_attached_SCSI
http://en.wikipedia.org/wiki/Backplanes
http://serverfault.com/questions/394990/what-is-the-max-supported-number-of-sata-devices-using-cable-adapters-on-a-del
http://www.sasexpanders.com/vs/sas-enclosures/
http://www.tomshardware.com/forum/268025-32-drives-connected-sata-port