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2 Bronze

Poor SSD performance on PERC 6/.i

Gentlemen?,

I recently bought a Precision T5500 that arrived with a PERC 6/i controller and 146GB 15K SAS drive.  The SAS drive performed very well for a mech'l drive- on Passmark Performance Test scoring 1208 on the composite disk benchmark. 

This was impressive enough that I decided to give SAS a whirl-literally- and bought a Dell 300GB 15K SAS drive.  The idea was to add a spare Samsung 840 250GB SSD as OS /applications drive and the data files would run on the 300GB SAS. and later add a RAID 1 of those.

However, when I added the 840 SSD on HDD0, the Passmark disk score for the Samsung was only 1128- lower than the SAS drive.  The 840 had scored 2600+ in it's former use on a desktop SATA III controller. 

I updated the firmware and driver for the PERC, verified AHCI, and whatever I could,  but can't see the problem so far.  I've read several comments of poor SSD performance on the 6/i but without explanation for it. On Passmark baselines there are a couple of T5500's with high disk scores- 6871 and 3469 and six T7500 systems above 3000. The single T3500 with a 6/i= 4820.  The fastest single mech'l drives on Passmark - which are 15K SAS- will score about 1400. I assume the top scores- over 5000- are probably a RAID 0 of SSD's and the second tier a fast single SSD.

With the poor score on the 6/i,  I tried the Samsung 840 on the SATA 2 channel 0 and it scored 2532- double the PERC score and closer to it's former rating on SATA III.

What am I missing?  If the SSD performance issue is not solved, I'll reluctantly need to remove the 6/i- which might be migrate to a Precision 390. Any ideas gratefully received.

Thanks!

PoultryLogistics

Dell Precision T5500: Xeon X5680 (6-core @ 3.33 / 3.6) , 24GB DDR3 1333 ECC reg'd, Quadro 4000, PERC 6/i with Samsung 840 250GB , Seagate Cheetah 15K SAS, Windows 7 Prof 64-bit

 

 

 

 

Replies (7)
7 Thorium

The PERC is an enterprise-class controller and requires enterprise-class drives. Enterprise-class SSD's are expensive, and although SSD technology is supported on a PERC 6, certified drives will likely be required for optimal performance. Although the T5500 is a desktop, it is designed with server-grade/enterprise-class components and should be treated differently than a regular consumer desktop.

8 Krypton

The 6i is a cacheless controller and very very very slow.

Its not a rocket Raid controller.  You get what you pay for or not.

http://www.newegg.com/Product/Product.aspx?Item=9SIA0ZX2E55255

http://www.highpoint-tech.com/USA_new/series_rr4520-Overview.htm

 

 


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Diagnostics & Tools

7 Thorium

You're thinking of the SAS 6/iR. The PERC 6/i is a different controller and has 256MB battery-backed cache.

8 Krypton

Dell PowerEdge Perc 6i SAS/SATA RAID Card DX481  is not a SATA III card however.  Expecting SATA 3 speed from a Sata 2 card is not reasonable.

PERC 6/E Adapter

3Gb/s SAS

PCI-Express 1.0

2x4 External

512MB
256 MB

Yes (TBBU)

144

Hardware RAID

PERC 6/I Integrated/ Adapter

3Gb/s SAS

PCI-Express 1.0

2x4 Internal

256MB

Yes (BBU)

16

Hardware RAID

PERC 6/I Modular

3Gb/s SAS

PCI-Express 1.0

1x4 Internal

256MB

Yes (BBU)

 

4

Hardware RAID

CERC 6/I Modular

3Gb/s SAS

PCI-Express 1.0

1x4 Internal

128MB

-

 

4

Hardware RAID

SAS 6/iR Integrated/ Adapter

3Gb/s SAS

PCI-Express 1.0

2x4 Internal

-

-

 

8

Hardware RAID

SAS 6/iR Modular

3Gb/s SAS

PCI-Express 1.0

1x4 Internal

-

-

4

Hardware RAID

 

 


Report Unresolved Customer Service Issues
here

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The forum is primarily user to user, with Dell employees moderating
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Diagnostics & Tools

2 Bronze

You might try setting the controller to Direct I/O for the SSD. also you might try turning off cache for the SSD. The big advantage of an SSD is IOPS (i.e no seek or latency due to mechanical movement).

2 Bronze

Combining SAS and SATA is not a viable configuration. You would be better off using one of the internal SATA ports for your SSD.

2 Bronze

The PERC 6I is an enterprise raid controller one thing it does to most drives is disable the drives write cache by default. You can toggle the drive write back cache setting by using megacli but it isn’t supported by dell. Not that dell really supports a raid controller coming up on a decade old mow

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