difference between PERC4e/DI and PERC4/DC RAID controllers for Dell servers

Posted on 2004-10-28
Last Modified: 2008-01-09

I've got 3 questions:

1) What's the difference between a PERC 4e/Di embedded dual channel RAID controller and a PERC4/DC U320 RAID Controller? The second one is much more expensive, both RAID controllers are dual channel, so it must have something to do with the technical specs of these RAID controllers? The first one is embedded and the second one is a PCI-X card you have to add, but there must be something else, performance on second RAID controller is maybe better?
2) Both RAID controllers have 2 channels? What are channels used for? Just to split the data traffic or...
3) I'm planning to attach 2 36GB U320 15k disks to the first channel and configure them in a RAID1 and attach 3 36GB U160 15k disks to the second channel and configure them in a RAID5. I'm planning to use this server as exchange 2003 server with system, paging, and transaction logs on the raid1 container and the database itself on the raid5 container.Is this a good plan or...? also two small subquestions?
     1) Is there much difference between U320 and U160?
     2) Is it okay to use the channels as I proposed above?

thanks in advance for any help,

Question by:jkumbruck
    LVL 9

    Expert Comment

    The Perc 4e/Di is embeded into the mother board. Your pricing entire MB with it.
    That might answer all your questions and point you to the U320, I don't know for sure
    DO NOT award me any points...I am just giving the info, not really answering your Q
    LVL 31

    Expert Comment

    2. You can connect differnt devices, for examble: Channel1 = internal strorage and channel 2= external storage device
    3.1 The differnce is the speed, to read or write you data

    LVL 31

    Expert Comment

    3. yes the logs should be on the raid1, because it is fast and there arent much data to write
    and the raid 5 for fast write and secure storing

    ...good solution

    3.2 in my opinion, it doesnt matter which channel you use for which device (raid)

    hope i could help you
    LVL 30

    Accepted Solution

    1: Speed - the 4/DC supports SCSI Ultra 320 - that is, 320MB/sec. PCI-X is also a considerably faster bus than PCI. You can also use the 4/DC in a cluster config. I don't believe that you canuse the 4e/Di in a cluster (but I'd have to check the documentation on that)
    2: If you can split the I/O load across 2 channels you can get better performance.
    3: Excellent plan! How many Exchange users will you have?

    3.1 160 MBytes/sec versus 320 MBytes/sec. First: a reality check. 320MB/s is a burst speed. Sustained throughput is much slower - due to the speed of the individual discs. 32-65MB/sec of a 15,000RPM individual disc is typical throughput. The best, absolute maximum perfect world (ie totally unrealistic) throughput you could hope to acheive on your listed config is 195MB/sec or thereabouts. Again, this is a burst speed. Go with U160 controller and discs and be happy! You've saved a lot of money and you haven't compromised performance one bit.

    3.2 Yes indeed! I would have recommended exactly what you've written. In a perfect world, you'd have a seperate mirrored pair for the Exchange logs, but you really only need to do that once you get to a large-ish Exchange organisation. You won't notice a performance hit by using the system discs for the logs - unless you fill the discs of course!

    Author Comment


    thanks for the answers!
    I've granted you all the points, but would really be happy if you could tell me more about the difference between the PERC4e/DI and the PERC4/DC RAID controller. The PERC4/DC RAID controller can be supplied with 2 internal channels, so this excludes the cluster option, there must be something else why this RAID controller is a lot more expensive then than the Perc4e/DI controller??

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