Re: [WinMac] how to justify a memory upgrade, part 2

Daniel L. Schwartz(expresso[at]snip.net)
Thu, 30 Dec 1999 10:21:01 -0500

        RAID "50" is not really an "official" RAID level, but it works well
nonetheless. However, there are two possible configurations - Two RAID
level 5 logical volumes striped, or mirrored. In either case, they are
inefficient in terms of storage space usage.

        Using the example of six 9 gig drives:

        A) If the two 3 drive RAID 5 volumes - At 18 gigs each - are striped,
you'll get 36 gigs of storage;

        B) If the two 3 drive RAID 5 volumes are mirrored, you'll only get 18 gigs
of storage.

        If they are striped (example "A" above), you still have failure exposure
because if two drives fail in the same three drive logical volume, you're
screwed.

 -----

        If it were me setting this server up - Depending on the RAID controller
firmware - I'd lump all 6 drives into a RAID 5 array, with 4 drives for
storage, one for parity, and one as a hot standby. This way, if any of the
5 spinning drives fail, then the 6th drive spins up and the array rebuilds
in the background. BTW, this is what IBM recommends with their ServeRAID
controllers in their Netfinity 5500 (& 5000 & 7000) servers. The 5500's
even have six hot-swap trays built in to the front! :)

        Cheers!
        Dan

At 12:05 PM 12/29/99 -0500, Tom Roth wrote:
>
>
>tom lyczko wrote:
>>
        [cut]

>> main usage at first will be file sharing, then various other things later
>> on...intranet?? who knows??
>>
>> i think 128 megs of ram is anemic, but how can i explain/justify this
>> in layman's terms???
>
>It will be very slow until you up the RAM. I'd guess you should at
>least double what you've got in RAM. WE have a PowerEdge 4200 with
>512MB of RAM, six 9GB HDs, DLT and of course SFM.
>
>> p.s. where can i find out how to set up RAID for NT????? and whether i need
>> raid 0, 1, or 5????
>
>Our PowerEdge came with a RAID built in and we create a RAID 50 (pair of
>RAID 5s) from the built in six 9GB hard drives.
>
> ______________________________________________________________________
> Tom Roth Wake Forest University School of Medicine
> tomroth@wfubmc.edu Dept of Biomedical Communications

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This archive was generated by hypermail 2.0b2 on Thu Dec 30 1999 - 08:42:33 PST