Re: SCSI Disk/Controller advice please - fun

From: Alvin Oga (aoga_at_ns.Linux-Consulting.com)
Date: 10/30/04

  • Next message: Alvin Oga: "Re: nv vs. nvidia - glx - today" 
    Date: Fri, 29 Oct 2004 16:48:08 -0700 (PDT)
To: Joao Clemente <jpcl@rnl.ist.utl.pt>

    hi ya

    On Sat, 30 Oct 2004, Joao Clemente wrote:

    > I'm getting a completly new server (P4 3Ghz, Dual-Channel DDR 400, MB
    > with intel chipset) and, while I have a good ideia on these components,
    > I would like to setup a RAID-1 system with SCSI disks...

    there is zero point ot setting up raid-1 if you do not need
    to be online 24x7

    problem with raid1 ( aka mirror )
            - if one disk goes bad, the other disk will copy that bad info
            onto the good disk .... the whole point of mirror, both disk
            is identical

    > I'm looking for advice on these: wich scsi controller should I buy?
    > Software or Hardware RAID-1? Wich disk brand? (I'm getting a couple of
    > 36GB, it is more than enough space for my setup)

    if you insist on using raid1 ...
            do software raid1 so you can monitor it and maintain it

    if you use hw raid1, you will suffer from not being able to monitor it
    and at the mercy of the hw vendor to provide you
    "monitoring/maintenance tools"

            - for the costs of the $200 hw raid1 controller, you can buy how
            many additional disks to do your "mirroring" with rsync and tar
            and other backup apps

    > Which are the tradeoffs of hard vs software raid1? What happens/How do
    > we proceed if 1 disk fails (how do we know it, how do we replace/resync
    > them?)

    with raid1 .. you're gonna be S.O.L if one disk dies in a bad way
    that will make the "good" disk also go bad

    > Seagate Cheetah 10K 68 pin, 36Gb - 160 EUR

    you're best bet

    but even better if you use ide sisks ... 250GB disks for $150
            or 40GB disk for $40 ... buy 4 disks ... why mirror to only 1 disk

    >
    > - Controllers
    > Several Adaptec SCSI Cards from 200 to 400 EUR, wich can have:
    > - 32 or 64bit

    there is zero point in plugging an expensive 64-bit controller into a
    32bit slot

    > - 160MB or Ultra320

    get ultra320 if you can ... and the ribbon cable to support that speed

    get adapaptec ... all other scsi controllers are NOT on the radar screen

    > - Raid (or not, when they say nothing.. I think) (the RAID ones start
    > at 400 EUR and I've seen up to 950 EUR)

    for that costs.. why is it an option ... you can build 1 or 2
    whole/complete systems for redundant power supply, redundant motherboard,
    redundant disks, redundant memory, etc, etc..

    not just one disk mirrored to another disk on the same system

    > Damn... Really confused... Please confirm these toughs also:

    :-)

    > UltraWideSCSI = 68 pin ...

    > What is "2", "3" or "4" ?!? These seem

    what sthe rest of the context ??

            scsi-2 scsi-3 scsi-4?? ( i don't think scsi goes up that far)

    > "similar" to ATA 66/100/133 - the bus speed, is that it?

    yeah.. maybe .. depending on where you "2" and "3" came from

    http://www.linux-1u.net/Disks/ata.gwif.html
    http://www.linux-1u.net/Disks/scsi.gwif.html

    > So, what's SCA? None of these controllers says SCA...

    sca is the silly removable connector on the disk and in the chassis to
    allow oyu to remove the disk

    > Ps: I supose getting a SCSI crontroller built-in on the motherboard is
    > stupid? Those are low-value/performance controllers?

    onboard controllers are brain-dead and worthless

    but its very good for teaching why you dont want to use it
    vs getting an adaptec to lsi logic scsi controller if you insist on scsi

    c ya
    alvin 

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