Results 1 to 5 of 5

Thread: RAID 5 Issues!

  1. #1
    3 Star Lounger
    Join Date
    Apr 2002
    Location
    UK
    Posts
    298
    Thanks
    6
    Thanked 0 Times in 0 Posts

    RAID 5 Issues!

    Hi,

    I have an ASUS P5ND2 775 SLi motherboard which I was using with 1Gb memory and a pair of SATA 150 80GB drives in a RAID 0 (non-redundant) stripe set quite happily with Windows XP Pro but being a PC phreak I have wanted to upgrade that for sometime.

    So yesterday I installed what I considered to be my dream disk system

  2. #2
    Platinum Lounger
    Join Date
    Jan 2001
    Location
    Quedgeley, Gloucester, England
    Posts
    5,333
    Thanks
    0
    Thanked 1 Time in 1 Post

    Re: RAID 5 Issues!

    Are you saying you are using software RAID, not a dedicated RAID controller card?

    John
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

    Ita, esto, quidcumque...

  3. #3
    3 Star Lounger
    Join Date
    Apr 2002
    Location
    UK
    Posts
    298
    Thanks
    6
    Thanked 0 Times in 0 Posts

    Re: RAID 5 Issues!

    Hi John,

    I'm using the onboard nVidia RAID controller exactly as I was for the pair of striped drives ... the 80Gb's are no longer in the system (the system only supports 4 SATA's anyway) so the system is effectively a completely new build (no OS as yet).

    Kyu

  4. #4
    Platinum Lounger
    Join Date
    Jan 2001
    Location
    Quedgeley, Gloucester, England
    Posts
    5,333
    Thanks
    0
    Thanked 1 Time in 1 Post

    Re: RAID 5 Issues!

    Conventional wisdom for servers used to be to have the operating system on a pair of RAID-1 disks, and 'user data' on as-many-as-you-have-room-for SCSI RAID-5 disks (I think we usually had [15 x 15000 rpm drives, with 1 'parity disk"] on each disk channel (yes, I know it doesn't work that way, but it was convenient to think of it like that). But that was using a Compaq RAID controller card costing well over
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

    Ita, esto, quidcumque...

  5. #5
    3 Star Lounger
    Join Date
    Apr 2002
    Location
    UK
    Posts
    298
    Thanks
    6
    Thanked 0 Times in 0 Posts

    Re: RAID 5 Issues!

    Hi John,

    Yes that's more or less the build configuration I use at work for our servers ... I've always thought that SCSI was better than ATA or SATA but the price difference is just far too big for me to be able to afford SCSI drives at home. My understanding of RAID 5 is that it's slower for writes (as there's more data) but faster for reads (how much so being dependent on the number of drives that data can be simultaneously read from).

    I haven't resolved the issue but I have got round it ... I figured that since my system worked well using 2 striped drives but worked (very) poorly using 4 drives in a RAID 5 config maybe, for whatever reason, the BIOS's (on board RAID controller) implementation of RAID 5 is poor.

    So I reconfigured the RAID 5 array to RAID 0 and that worked fine and gave me 1.2 terabytes of disk space ...of course that means the disk set is no longer redundant. I suppose I could try either RAID 0+1 (striped mirrors) or RAID 10 (mirrored stripes ... not entirely sure what the difference is there) which would return me to a redundant system but reduce my available disk space to 0.6tb which is more than enough (though I am conceited enough to admit I like having that much space whether I used it or not).

    Anyway ... suffice it to say that the system currently works well in RAID 0. Given that the system was previously build on 2 80GB SATA 150 disks (striped) I was curious what the benefit, if any, I might get from the new configuration. Despite the technical specifications, in real life SATA II (300Mb/sec) apparently does not perform significantly better than SATA I (150Mb/sec) but I nevertheless measured the disk speed for all three disk types used in my system with HD Tach with the following results:

    1. Maxtor 160Gb ATA/133 8Mb cache, 92Mb/sec
    2. 2 x Seagate 80Gb SATA 150 8Mb (striped), 169Mb/sec
    3. 4 x Seagate 320Gb SATA 300 16Mb (striped), 221Mb/sec

    So there is some improvement but I am not sure whether the SATA II or the additional disk drives is the key to that speed increase ... my best guess is that it's a combination of factors but that the number of disks in the array is the most important one.

    Anyway, thanks for your help [img]/forums/images/smilies/smile.gif[/img]

    Kyu

    p.s. Yes, in the manual I just downloaded from the ASUS site it does suggest it can support a combination SATA/ATA RAID array which I suppose would be useful if space was your primary consideration.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •