ASUS P6T6 WS SAS Expander

[sgrinavi]

I was looking at this ASUS P6T6 WS Revolution board and wondering about the 2 2 x SAS ports and the expander.

Marvell 88SE6320 SAS controller
2 x SAS ports supporting SAS RAID 0, 1, 10*
Marvell 88SE6121 SATA controller
2 x eSATA 150/300

* A SAS expander (excluded in package) is required while using RAID 10 on SAS ports.

The only thing I can find on the expanders that makes any sense to me leads me to believe that I am barking up the wrong tree. Everything else I see are large boxes that look like rack mounted HD drive arrays

Am I missing something here or is Asus trying to pull a fast one?

 

[VaultDweller]

Most SAS expanders are rack-mounted drive arrays, or built into rack-mounted cases with many drive bays. This is the only place there is really any kind of market for SAS expanders.

What exactly are you trying to accomplish?

 

[sgrinavi]

Originally posted by: VaultDweller
Most SAS expanders are rack-mounted drive arrays, or built into rack-mounted cases with many drive bays. This is the only place there is really any kind of market for SAS expanders.

What exactly are you trying to accomplish?

I would like to run 2 sets of 4 drive arrays.. A RAID 0 for my apps and a RAID 10 (or 0+1) for my data.

Currently I have settled for a 3 drive Vertex-120 SSD array for my apps (which, actually, is faster than the 4 drive array I tested) and I have my data on a 3 drive (WD640AAKS) raid 5 array. I am not unhappy, but would be happier with MOAR!

 

[Rubycon]

The SAS controller on the P6T6WS is a waste since it has SATA connectors instead of miniSAS connectors. The latter allow four drives per channel with a fanout cable. Most server boards will have these connectors eliminating the need for an expander which can be costly.

 

[pjkenned]

Originally posted by: Rubycon
The SAS controller on the P6T6WS is a waste since it has SATA connectors instead of miniSAS connectors. The latter allow four drives per channel with a fanout cable. Most server boards will have these connectors eliminating the need for an expander which can be costly.

Well of course you might want to run two Savvio 15k.2's on your WS... but I still think that anyone who is into 15k rpm SAS drives probably is going to be using a dedicated card. I couldn't imagine having the 8x savvios on something onboard versus the 5805. It is probably cheaper/better to buy a 8 port raid card versus an expander anyway since running raid 0 with more than two drives gets really scary.

 

[VaultDweller]

Originally posted by: sgrinavi

Originally posted by: VaultDweller
Most SAS expanders are rack-mounted drive arrays, or built into rack-mounted cases with many drive bays. This is the only place there is really any kind of market for SAS expanders.

What exactly are you trying to accomplish?

I would like to run 2 sets of 4 drive arrays.. A RAID 0 for my apps and a RAID 10 (or 0+1) for my data.

Currently I have settled for a 3 drive Vertex-120 SSD array for my apps (which, actually, is faster than the 4 drive array I tested) and I have my data on a 3 drive (WD640AAKS) raid 5 array. I am not unhappy, but would be happier with MOAR!

I think you'd be better off just getting an add-in card. RAID-10 has no parity, so even a cheap host-based controller is fine.

 

[Rubycon]

Originally posted by: pjkenned

Well of course you might want to run two Savvio 15k.2's on your WS... but I still think that anyone who is into 15k rpm SAS drives probably is going to be using a dedicated card. I couldn't imagine having the 8x savvios on something onboard versus the 5805. It is probably cheaper/better to buy a 8 port raid card versus an expander anyway since running raid 0 with more than two drives gets really scary.

RAID0 w/10 drives here, no worries. Even had one getting errors and Windows would complain that it could not find a file, etc. Pulled the drive, put in a replacement, formatted and back online. Now if you actually have something important and don't have a good backup that's like playing Russian Roulette with perhaps three bullets in the gun! :laugh:

 

[pjkenned]

That scares me! Then again, I hate having any downtime so I'm a bit of a wimp in that area... even with raid 5 arrays utilizing raid 6 network backups I still get nervous. I lost a backed up array (lost 26 hours of data) about 5 years ago due to a 2-drive raid 0 and won't go back.

 

[Rubycon]

I have a simple policy - don't keep anything of value on the array for any period of time. It's a great tool for scratching. The OS flies off it and with 2GB cache misses are infrequent so performance is higher than SSD's.

 

[pjkenned]

I totally understand where you are coming from. Even my Raid 5 array is 550MB/s write 650MB/s read. I have been extremely happy especially when doing multiple tasks that hit the disk simultaneously. Seems that the same workload that made the i7 a no-brainer is the same workload that loves the HW raid and multiple disks. Then again, the 36GB Savvios are not really sequential read/write monsters since they are 2.5" drives so raid 0 would be a bit less fun.

One of these days I would LOVE to get an ARC 12xx SATA card, throw tons of cache on it, and try two arrays one with notebook drives and another with fewer desktop drives just to see the performance/ power/ cooling requirement difference is.