[mdlug] Reordeing IDE drives in a system

[Joseph C. Bender]

Dan Pritts wrote:

> On a related note, has anyone played with SATA port multipliers?
> 
	Yes.

	Don't.

	The underlying SATA controller has to be able to deal with it.  There 
have been certain cheap chipsets that don't work with multipliers all 
that well.

	Additionally, you'll limit your disk I/O greatly, because all the disks 
will be sharing one SATA link back to the controller.  The money would 
be better spent on a SATA JBOD or RAID board where every disk gets a 
dedicated channel.

	I had a project where the hardware had already been bought by Someone 
Else (which should have been my first warning we'd have problems), and 
included one of these beasties.  Disk performance was utterly, utterly 
terrible.  Between the shared SATA channel and the md() RAID setup, 
things like Samba transfers couldn't even saturate a 100mbit link. 
Eventually, we scrapped it and got a pair of 3Ware multi-channel RAID 
controllers to deal with the problem, once I convinced them that the 
hardware was inadequate.




-- 
Joseph Bender
Bendorius Consulting
P: 248-434-5580
F: 248-434-5581
jcbender at bendorius com