[OpenIndiana-discuss] Expanding storage with JBOD

[Edward Ned Harvey (openindiana)]

> From: Saso Kiselkov [mailto:skiselkov.ml at gmail.com]
> 
> Nope, SATA does have port multipliers, though I agree that beyond a certain
> point it becomes a mess.

Now that you mention it, when I look around, everything that I find called a SATA port multiplier is some sort of add-on card that takes an upstream SATA port and gives you several downstream SATA ports.  I don't see the point.  If you have room for an add-on card, I would think, it would make more sense to just add another SATA adapter to the PCIe bus.

The main point is, a port multiplier might be useful if it's *outside* your system.  Supposing you have an external enclosure that holds 4 drives or something like that...  You might say, "I have SATA 6Gbit bus which is good enough for the 4 drives in that enclosure."  And I would tend to agree, if they let you run a single 6Gbit SATA cable to the enclosure and then internally they use a SATA port multiplier, that would be pretty nice.  But when I look around, I don't see any 4-drive enclosures that use a single upstream 6Gbit ESATA bus...  I see enclosures with 4 bays, and 4 ESATA ports.  One for each drive.  By comparison, the same exact class of products certainly exist, with 4 drives (or even 16 or 24) on a single SAS (Mini-SAS, SFF-8088) cable.  Internally, the enclosures have SAS Expander to fanout to the drives.