SAS versus SATA Hard Drive for Dell Precision T7500 Workstation

Posted on 2009-05-19
Last Modified: 2012-05-07
One more question comes up as I configure a Dell Precision T7500 Workstation.

The workstation will be used as a PC, not as a server. It will be on about 15 hours per day although not in active use all that time.

I plan to purchase the system with one internal hard drive from Dell configured in non-RAID. I plan to add one internal drive on my own rather than paying Dell to do it. One drive will be for OS/applications and one drive will be for data. (The data gets backed up offsite through the day and to an external drive at night, so I am comfortable with no RAID.)

I had been planning Western Digital 10,000 RPM 300 GB Velociraptor drives. Then I noticed that Dell offers either SATA or SAS drive configurations. In the configurator they describe it as "all SATA" or "all SAS." In the T7500 specifications for the hard disk controller they list:

Integrated LSI 1068e SAS/SATA 3.0Gb/s controller supports host based RAID 0 or 1
Optional PERC 6/i PCI-e SAS/SATA hardware RAID card supports RAID 0, 1, 5, 10

The SATA drives Dell offers are 10,000 RPM 3.0 GB/s drives. The SAS drives they offer are 15,000 RPM 3.0 GB/s drives.

Curiously there is no price difference for the same capacity drive in either SAS or SATA.

Which do you think I should choose? Why? Will adding a drive be more or less difficult with SAS compared to SATA?

Thank you!
Question by:Peter Bye
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LVL 22

Expert Comment

ID: 24428321
SAS will be faster.
Make sure there is a driver for the SCSI/SAS controller for your OS, if planning on XP you probably have to install the driver (hit F6) during the installation so that the OS can see the drive.  Otherwise, SAS drives are not any more difficult to install over SATA.

Author Comment

by:Peter Bye
ID: 24428346
Chakko's comment points out that I should have mentioned the OS plan.

I plan to order the workstation with XP Pro 64-bit and update to Windows 7 64-bit when it becomes available.
LVL 10

Expert Comment

ID: 24428610
If the machine is running for extended periods then you want a good MTBF, check the specs on the drives in question. It's open to argument but generally scsi drives are recommended for prolonged use.
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Assisted Solution

estaticd earned 225 total points
ID: 24428621
SAS controllers are backwards compatible with SATA drives.  Most (if not all) SAS drives are optimized for server performance,   In almost all cases, Raptors will be better for desktop usage.

Read the section on Desktop / Workstation here:

"WD's newest Raptor delivers the best single-user performance one can buy regardless of interface and spindle speed."
LVL 69

Expert Comment

ID: 24431062
The SAS drives will give you better performance, as they spin at 15,000 rpm vs 10,000 rpm for the Raptor. Dell doesn't charge any more for the SAS drive because the Raptor is a very expensive SATA drive - run-of-the-mill SATA drives are a quarter the cost of the Raptors. If Dell lets you configure a machine with the SAS drives and the OS you choose, it will have the driver for the controller. Keep in mind that you will need to spend more money in the future if you buy additional SAS drives, as opposed to SATA drives.

Author Comment

by:Peter Bye
ID: 24431809
The review posted by estaticd is very impressive although the review dates from April 2008. StorageReview finds that the VelociRaptor is faster and quieter for single-user applications while consuming less power than other drives including the Seagate Cheetah NS (400 GB) 15,000 RPM SAS drive.

Does the review modify anyone's thoughts about VelociRaptor versus SAS drives for this single-user workstation application?

I am contemplating asking Dell if they can configure with the PERC 6/i PCI-e SAS/SATA  controller and VelociRaptor 300 GB drive. The purpose for the SAS/SATA controller would simply be to maintain future flexibility.

Your thoughts?
LVL 69

Accepted Solution

Callandor earned 275 total points
ID: 24432444
StorageReview is pretty thorough, so I would agree with their findings.  The SAS drives are better in multitasking environments where they can use tagged command queueing.  This is better for servers and databases, but I can see it also being useful for very active individuals who run queries, encode video and audio, code and debug and perhaps play games simultaneously - in other words, an uber power user.  If the normal pattern is sequential single tasks, then SAS will not benefit and the VelociRaptor is much better.  Now if you had an Ultra320 controller, the Fujitsu MAU3147 would rule.
LVL 69

Expert Comment

ID: 24433699
As food for thought, I thought I'd look further into the Fujitsu SAS drives.  Many customers thought highly of this Fujitsu MBA3147RC:  It seems some preferred it over the Raptor.

Author Comment

by:Peter Bye
ID: 24437814
Thank you everyone. Callandor and estaticd in particular - you both have provided outstanding information and insight. Knowing a lot more now, though, I confess to still being "on the fence". The ball is in my court at this point.

My leaning at the moment is towards the VelociRaptor for these reasons:

* The StorageReview tests showed the SAS and VelociRaptor very close together in performance, although the test was with a 10,000 RPM SAS drive and not a 15,000 RPM SAS drive.

* Elsewhere, I've seen admonishments to people like me that a power user really isn't like the fully-random access that a server sees, and that we're more like an individual user than we think.

* I can probably influence Dell to equip the WD VelociRaptor since they specify it on some of their models. I probably have no influence over the choice of SAS drive they use.

I provide this update in case it spurs more thoughts, any of which will be valued and appreciated. Regardless, I will close and award points on Thursday.
LVL 69

Expert Comment

ID: 24437961
If you can get the Fujitsu MBA3147RC SAS drive, it performs the same as the VelociRaptor in single user mode for a single drive, based on the throughput numbers users posted on newegg - 119MB/sec single is about the same, but 276MB/sec in RAID-0 is very good, if it really does that.  If they don't let you specify the drive, then buying it separately still isn't that bad - $180 for one.

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