Linked by Thom Holwerda on Thu 8th Jan 2009 18:47 UTC
Hardware, Embedded Systems SCSI (Small Computer System Interface), often called parallel SCSI, is almost 30 years old and can hardly keep up with the demands of today's IT environment. Serial Attached SCSI (SAS) was developed to address the limitations inherent in SCSI. This article highlights the differences between these two interfaces and points out the attributes that account for the increasing popularity of SAS.
Order by: Score:
Comment by dvzt
by dvzt on Thu 8th Jan 2009 20:53 UTC
Member since:

There is a mistake in the article. SAS top speed is not 3 GB/s, but 3 Gb/s (bits not bytes).
IBM messed something up again ;)

Reply Score: 2

RE: Comment by dvzt
by gfolkert on Thu 8th Jan 2009 22:19 UTC in reply to "Comment by dvzt"
gfolkert Member since:

No, I am sorry. That would be WAY to fast for the (actual) drives throughput on the hardware itself, not even mentioning the interfaces.

3 Gigabit/sec == 300+MB/sec (depending on your source and setup supposedly 322MB/sec w/o EC)

3GigaBytes/sec == at least 24Gigabits/sec without any form of correction

Parallel SCSI has been stuck at "U320" for a while, and it has never been able to really truly been able to sustain (even close to) 320MB/sec.

Hey, lets look at the controllers... oh look at that, models from Adaptec, Mega (et al) all focused on the same chipsets... supporting either SAS or SATAII at 3G-BIT PER SECOND

Lets think on that before we jump.

My Edit... leaving for proof I'm an idiot:
And YES, I now read comment properly. (BAD GREG! Naughty GREG!)

Edited 2009-01-08 22:22 UTC

Reply Score: 2

RE: Comment by dvzt
by dizzey on Sat 10th Jan 2009 03:26 UTC in reply to "Comment by dvzt"
dizzey Member since:

yeah it's bad maners to use gbit vs mbyte in the comparison. on quick read people will go ooh sas is so much faster.

of course sas will have that speed to every disk so it's good for raid systems and such.

then again when people need lots of disk's they use external cabinets for those and they still only use one cable to connect all of the disk's so then we are back to the same problems of many disk's sharing one bus that goes around 300MB/s

Reply Score: 1

RE[2]: Comment by dvzt
by zlynx on Sat 10th Jan 2009 09:08 UTC in reply to "RE: Comment by dvzt"
zlynx Member since:

People used to connect external cabinets with a single SCSI cable, but not lately.

It might be a single cable, but these days it is likely to be Infiniband or a PCI-Express variant.

Reply Score: 1

RE[2]: Comment by dvzt
by tsedlmeyer on Mon 12th Jan 2009 18:12 UTC in reply to "RE: Comment by dvzt"
tsedlmeyer Member since:

People needing lots of external storage connect via fibre channel with multiple paths for redundancy and performance. Currently fibre channel products are available in speeds up to 8Gbs per connection.

Also fibre channel over ethernet (FCoE) or iSCSI via 10Gbs ethernet are alternatives for high speed external storage. Again multiple paths can be used for redundancy and performance.

Reply Score: 1