SAS disks on SATA ports?

[pointertovoid]

Hello everybody!

Everything is in the title once again... I've read that Sas, the "Serial Attached Scsi", is meant to be compatible with Serial Ata. But does someone here have feedback (maybe practical experience) on that?

I mean: can I just buy a 15.000/min Cheetah or Ultrastar or equivalent and use it on a standard S-Ata mobo, for instance an Ich10r?

Or can a simple electrical adapter do the trick?

Or did this compatibility attempt go wrong, or did I misinterpret?

And in case it works: does one get significant Scsi performance when connecting to a S-Ata II port? And in Raid-0?

And by the way: how noisy is now a 15.000/min Scsi disk nowadays? Last time I heard Scsi disks, one wouldn't stay willingly within their special room, which was covered with sound absorbers.

Thanks!

[Tripredacus]

I'm also kinda confused on this subject. The computer in my servers named 7Server has a HDD enclosure (internal) with a SAS backplane (because I had to replace it) and has 3 SATA drives connected to it. But I am not running SCSI drives or anything remotely relating to that.

[iamtheky]

Plenty of ridiculously in depth articles, but this one is a nice overview

http://findarticles.com/p/articles/mi_m0BR...23/ai_105884200

How SAS/SATA Compatibility Works

The SAS backplane connector was designed to accept either a SAS drive or a SATA drive, while making provisions for a dual-ported SAS drive. SAS connectors add a notch to the SATA connector to ensure that SAS drives can only be plugged into SAS systems. This is required because SATA host controllers do not understand SCSI protocols and will not recognize a SAS drive. Notching the SAS drive connector prevents a SAS drive from being plugged into a SATA host controller, which would result in a non-functioning drive.

[pointertovoid]

Thanks iamtheky, this really helps!

So if I have a standard workstation mobo (hence with Sata ports) and want higher performance from my storage, I can

- Buy a Sata Flash disk up to 300MB/s and 0ms (or several ones in Raid);

- Or add an Sas raid controller on a Pci-E x4 or x8 and connect Scsi-sas disks there.

But I can't connect Scsi-sas disks directly on the Sata ports of, say, an Ich10r.

That's clear now!

By the way, I used to consider that a Raid controller adds 8s boot time because of its own Bios, which offsets the benefits of loading the OS faster. But I've just seen that RocketRaid (and hopefully others) now offers to adjust this wait time through their tuning software. So if they propose 1s or 2s, the biggest drawback I see is now gone.

Edited March 31, 2009 by pointertovoid

[Tripredacus]

I've never been too concerned with boot times and RAID controllers, because I only use RAID controllers in servers. Boot time isn't super critical because if I am constantly rebooting the server, then something is wrong.