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SATA RAID ISSUE

I am not sure idf this falls under hardware or software but....

I have just deployed a Dell 745N NAS w/ SATA Raid 5

I migrated from a Dell Power Edge 6450 w/ SCSI  Raid  (PERC3)

My issue is with Large Excel files. Anything over 2 MB takes 5 minutes to load. We have spreadsheets that are 25MB and more. So you can see my issue.

We did not have this isssue on the SCSI Drives.

I am told by Dell that it is the SATA Raid Controller that is my problem it can not handle the cache requirements.

I have to call BS and ask someone that knows what they are talking about.

SCSI and SATA use caching differently. SATA actually uses the cache on the drives to increase read/write performance. Yes? No?

Has anyone experienced this before? Or Any suggestions on where to find a real solution?

Thanks
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catchone
Asked:
catchone
1 Solution
 
jamietonerCommented:
Your going to notice a performance decrease going from your old setup to the new one. Mainly because your old scsi drives (u160 max xfer rating of 160MB/s and either 10,000 or 15,000 rpms)  with the raid 5 on a controller that had 128mb of cache on the controller. The new system has a sata raid controller (the sata drive that shipped with that system are sata 1 max xfer rate of 150MB/s and 7200 rpms), depending on what raid controller it is as it comes with 2 raid options first option is a software raid 5, which means the only cache being utilized is the cache on the hdds and it has to use the cpu to calculate the parity tasks and is controlled by the operating system, 2nd option is a hardware raid, Im taking an educated guess that its the Cerc sata 6 (since it isnt specifically mentioned in the specs what sata raid controller is used, but the cerc sata 6 is the only option for sata raid drivers for the system) which has 64mb of cache built in which isnt to bad but the perc 3 scsi controller is going to be faster. By the performance issues your seeing i bet your using the software raid which is going to perform worse than the hardware raid using the cerc. The other possibility is that they are using a driver based hardware raid using sata ports on the motherboard the only big differences between this and a software raid is, you have to setup the raid in a controller bios, and instead of the os controlling the raid a driver controlls it, but it still uses the main cpu to process the parity and the controller has no cache. This setup is possible but dell would usualy have the driver for this setup listed under the sata raid drivers on thier website and i'm only seeing the Cerc sata 6 under sata raid drivers but that doesnt mean that they just didnt put them there and that may be the setup your running. What you may want to do is hook the 6450 back up and just use it as a storage server on the network as it will be faster than the 745n.
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CarlosMMartinsCommented:
Well, that sounds like an issue...
Sata HDs can (and should) behave much better than that. Either your drivers are not working properly, or there is some "incompatibilty" in your system.

A friend of mine once had a few quirks, with a controller that would disable the Hard disks inbuilt cache, causing a major performance hit - and had to use a "beta" bios, to correct the issue.

Also, you can try a quick test: to see if the issue is actually the file reading, or the excel software.
If you copy a 25Mb file to another folder, does it take that long to copy?
Or is it just when opening the excel files?
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jhanceCommented:
I don't this this is a caching issue and I also don't think that what Dell is telling you is in any way correct.  A 2MB Excel file in 5 minutes!!!  Give me a break, there is something seriously wrong with this hardware!!

Even a lowly IDE drive is faster than this.  There can be performanced differences between SATA and SCSI RAID but they are really only going to show up under high-load conditions.  Yes, the SCSI drives are somewhat faster and the SCSI RAID controller is a little faster but we're talking minutes to load a file that should take seconds.

In my experience with Dell (as well as other tech support) their #1 priority is to close the call.  They often try to do that by blaming you for making poor decisions.  Don't accept this treatment.  PUSH for then to take care of their problem.

There is nothing wrong with the SATA or the SATA RAID technology.  There is something wrong with your hardware, however.
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CallandorCommented:
Anything that takes that long to transfer such a small amount must have a hardware problem.  You should check the cables and the access mode of the drives in the BIOS.  What Dell told you is a lot of nonsense - calculate how fast it takes for a cache to empty at 150MB/sec and you will see that it is nothing on the order of minutes.  Once the cache is empty, even a non-RAID drive will deliver data around 50MB/sec; a RAID-5 will be faster.
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rindiCommented:
What type of network connection are you looking at between the NAS and your users? 10MB, 100MB or 1GB?

Make sure your LAN has enough throughput, and put a switch between the devices, not a hub.

Can you connect the NAS directly to a PC with a crossover cable, and what type of data transfer do you get then?
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catchoneAuthor Commented:
Thank You all for your input. Excellent information.
The Dell Techs had me going in the wrong direction.

The NAS Device had a faulty NIC. Even set manually at 100/ Full on both NIC and Switch. It was still trying to negotiate a port speed.

Switched to the 2nd Nic and all is well.

I am going to go back to DELL and express my displeasure in there support of this issue.

Thank You Again for getting me back on track.

Just as a side note Cache was disables on the Sata Controller and I did enable it.
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rindiCommented:
Thanks.
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