"Dream (Windows Desktop) System" - Please Critique

[jbucks]

[The Gorn]

What is the typical difference in disk I/O throughput between a SAS drive based workstation, no RAID, one HDD, and a comparably equipped SATA drive based workstation?

I read in some blog that there is typically a 3:1 throughput and latency speed advantage of SCSI and SAS over SATA.

I can see that this would be a huge advantage in any disk IO related operation (like, for instance, booting into Windows.)

[Aussie]

For the benefit of impoverished ex-mainframe proggies, could you please post a few open-box photos when you accumulate the makings of this project?  I promise not to drool on it.

[Richardk]

I wonder where's the bottleneck? In the controller or the drive? Is there a performance advantage with a SAS controller and SATA drives?

If you go with "big drives" then it seems that the MB will accommodate your needs. On the other hand the SAS cards look 'really nice' but unless you're building a 'disk drive farm' or see a significant performance difference, I don't think you "need" it but it's something to consider.

Your concern about booting is something to consider as well, at least go with a 'name brand'. I picked up a RAID card some years back to add some additional disks and even though I didn't use the RAID features, from Windows point of view, all those additional disks look like SCSI drives. So if the card goes, I'm in trouble if I don't have good backups. I don't know if this applies to SAS controllers as well.

[The Gorn]

The aspect of requiring a diskette is specifically with any disk controller for which Windows 7 does not have a built in vendor driver that can talk to the controller. So a RAID configuration I did here a few years ago needed a diskette, as would the Adaptec 1405 SAS controller. It's not a SCSI/SAS thing, it's just that Windows doesn't have the driver (yet, or maybe ever.)

Re: Bottleneck , here is what I understand.

SCSI (and SAS, which is a specific type of SCSI) defines a tagged command structure. So the CPU can send disk IO commands to the controller and the controller can execute the commands in whatever order results in fastest execution. Disk drives and controllers for SCSI and SAS are expensive because each end (HDD and controller) needs a microprocessor to deal with the commands. These are smart HDDs and smart controllers.

SATA, IDE and ATA are "dumb" protocols and the HDD doesn't have that level of smarts to queue commands asynchronously.

NOW... having said that....

I am highly skeptical that a workstation application will take real advantage of a SAS or SCSI drive. Where I would see SAS shining is in server and highly concurrent multi-user applications. I suspect that the full power of a SAS drive/controller would be underused on a workstation, even a developer's PC.

Thoughts on this, guys?

[Richardk]

Part of the cost is that you're off loading the disk I/O to the controller and drive. So SCSI and I'm guessing SAS do the "work" while the CPU runs off to do something else.

I agree that it's unlikely a workstation can push disk I/O enough for it to matter in day to day use.

[The Gorn]

Overall, cost for the system (including the OS - trying to wean myself off of MS Action Pack this year) - is about $1200 (USD). Yes, I'll take some pictures for the gang.

That modest price level buys an exceptional level of CPU power and speed today. It's just amazing.

[DarkHumour]

In 1995 my Pentium 133, socket 7 motherboard (off brand), and 16MB of RAM was at least this much ($1200 plus).  This was through the good old Computer Shopper.

I should have clarified my examples with SCSI.  My experiences were with parallel scsi not SAS.  I didn't think the details were important but here they are..

I had a superseven motherboard from Epox* and was trying to use a PCI-X scsi controller on it.  Adaptec had a 29160 and 29160N as options.  The N model was a "narrow" pci card, the former was supposed to be backwards compatible (with bandwidth adjusting accordingly).  I didn't want to go with the "N" card if I happened to invest in a motherboard with a PCI-X slot in the future.

I ordered the 29160 from buy.com and it refused to boot if I had a hard drive attached to it. I returned it. Received another one. Same problem.  Tech support told me "Oh yeah. Doesn't work. Buy the "N" model.  I did some exhaustive research and found a rebranded LSI card (Tek Something) with similar specifications.  I don't recall the model number but I think the chipset was 53C1020 or 53C1030.  Later I bought another similar card and ran that in my server (retiring my Adaptec 2940W and/or SIIG knockoff version of that card).

I liked the low profile options that LSI offered and I'm kind of partial to the 8208 SAS controller model but I haven't checked on reliability or reviews for SAS as I can't afford it probably until Q2 or Q3 2010.  I may even go with something completely different than Adaptec or LSI.

My LSI Card with Seagate hard drives booted and functioned fine for years.  I actually still have it after I decided to go SATA in my server "temporarily".  I think the only scsi drive that croaked was because I didn't have fans cooling it properly (they were off or had failed) it was under warranty and replaced.   All of my parallel scsi drives are out of warranty now but still work.

The other reason I went with SCSI was that their warranty was 5 years while pata and sata was only 1.   I think Seagate has expanded all of their new drives to be five years now.


There are a few "cheats" to bypass that F6 boot disk nonsense in recovery console.  I think I may have posted it under a "brain transplant-how to" on here.  Involves copying the driver to cmdcons folder and changing a couple of lines of text in txtsetup.sif.

Slightly overstated way

I try to do this right away so if there is a problem I don't have to find another computer, a floppy that isn't damaged out of the box, and copy the drivers to it.... and in some cases figure out how to do it without a floppy drive.

Hmm. I still need to add SATA's AHCI drivers to recovery console on a few computers.

Meanwhile I'm having "fun" with netsh and wim files.  Joy.

DarkHumour

PS.  I have a friend who is (jokingly ... I think..) a fibre channel fanatic.  Surprised no one has come out of the woodwork to crow about that interface.    

edit: clarity - *In 2009 that motherboard was finally replaced (was still working) and momentarily orphaned and probably thrown out (along with the K6-3 proc) when I left it in an office too long.

[jbucks]

[pxsant]

I would skip the SAS drive option and stick with SATA. If you have a problem down the road, you want to be able to get a replacement at the corner drug store. Besides, this mobo has 6 SATA connectors, lots of possible combinations. My only question is your choice of drive size. The price difference between a 1 TB and a 1.5 - 2.5 is relatively insignificant. I might add a second 1 to 1.5 as an external drive using an open docking station like the Thermalake
http://www.microcenter.com/single_product_results.phtml?product_id=0280775

BTW, I seem to have lost the ability to post a shortcut link. Anyone remember where that setting is?

[The Gorn]

I would skip the SAS drive option and stick with SATA. If you have a problem down the road, you want to be able to get a replacement at the corner drug   store. Besides, this mobo has 6 SATA connectors, lots of possible combinations. My only question is your choice of drive size. The price difference between a   1 TB and a 1.5 - 2.5 is relatively insignificant. I might add a second 1 to 1.5 as an external drive using an open docking station like the Thermalake  
  http://www.microcenter.com/single_product_results.phtml?product_id=0280775

That is also the conclusion I came too. I stumbled on a white paper for enterprise storage by a vendor like Seagate or Adaptec, and they were saying essentially that there is little reason to consider SAS or SCSI for even a high end workstation.

A workstation in my hands is not a 24x7 proposition. And I have a backup regimen in place.

The one exception I ran across in perusing some help sites (like serverfault.com) is that database work right on the workstation could take advantage of SAS speed, maybe.

BTW, I seem to have lost the ability to post a shortcut link. Anyone remember where that setting is?

The automatic link creation works for me on and off (IOW, it's flaky as hell.)

You *should* have editor buttons at the top of the edit windows for this forum. Find the "chain link" icons - one is a link, the one to the right is a broken link. Highlight the failed link text, and click the unbroken link. You should see a place to enter the URL in a popup window that appears.

[DarkHumour]

If it wasn't clear I was advocating the SAS controller and maybe SAS drives later. (If sata proves to be not reliable enough).  Especially if you are considering even a simple raid array.

(Yeah, there are fancy schmancy sata raid controllers with memory,cache, water-into-wine but if you're going to buy an add-in controller why not go SAS as it is compatible with both.)

I'd also recommend the 2.5" sized drives of any interface over the 3.5" ones.  (Unless there is some specific cache, quirk, or feature that will positively affect performance that is only available in 3.5" version).

The great thing about standards is...

there are so many of them.

DarkHumour

PS.  My wholesale vendor has 80g 2.5" sata drives for under $30 each.  Hmm... do I really need to eat next month? (I would make a 3 or 4 drive raid 5 array with those).

[The Gorn]

The increase in price of the overall system to go SAS, without any quantifiable basis for better performance expectation, is not the only stumbling block, although it is a big disincentive.

What is, for me, the show stopper - is the extremely limited selection of affordable SAS controller options - there are like literally maybe two product choices under $200 - and the fact that the controllers at this level are generally not supported directly by Windows 7, so you use an outboard driver diskette.

I saw your hack for getting around driver diskettes - a very good hack, btw - but there are enough science fair aspects to this new system that I now really want to limit the variables that can cause failure or frustration. I'm using the newish Intel i7 CPU, 12 GB of ram (geez), and Windows 7 (never even saw it outside a retail store before this.)

But, thanks for expanding my horizons (also the same to jbucks.)

Just to put this in perspective - this is an attractive option to you guys (you and jbucks) because you know exactly what you're talking about. For me it's an unexpected and fairly unwanted (at least at this point) learning curve and still kind of mysterious.

[DarkHumour]

I can see a sorcerer's apprentice reaction while SAS hard drives march in and take over your home office.  Watch helplessly as they compulsively fill everything with ones and zeros.

Good Luck with Gonzo Box v1.0

DarkHumour

[The Gorn]

I can see a sorcerer's apprentice reaction while SAS hard drives march in and take over your home office. Watch helplessly as they compulsively fill   everything with ones and zeros.  
 
  Good Luck with Gonzo Box v1.0  
 
  DarkHumour

You've got it nailed... lol.