SATA Port multipliers

[dchamb]

Hello everyone

 

My unRAID cabinet and motherboard is running out of space for additional SATA drives. I've been looking into port multipliers with eSATA and expanding to an external cabinet. However, I don't know a whole lot about port multipliers and would like to know from this group if anyone has implemented it under unRAID 6. Any issues?

 

Thanks

 

Dale

[RobJ]

Just a general comment, I'd wait for other more specific comments -

 

Port multipliers do work, are a relatively cheap way to add more drives, and should be no problem with unRAID v6.  The big downside is that they are a significant bandwidth bottleneck.  I'd put as few drives on it as possible, as they all have to share the one pathway, which may not be very fast.  That may be fine for single drive access, but means much slower parity checks and builds, and drive rebuilds.  Single drive access is more important of course, the others are maintenance tasks.

[BobPhoenix]

Another though is a SAS expander if your controller will work with one (Do have and IBM1015/LSI 9240-8i/LSI 9211-8i class controller connected to your drives?).  You then get a external cabnet that has a SAS connection an route a cable from the expander to the external cabnet.  SAS expanders allow much faster access but still reduce the parity check speeds by about 25% based on my analysis on a 16 drive array.