[plug] Comments on Mylex RAID cards in Linux requested

Steve Baker sbaker at icg.net.au
Thu Apr 27 10:01:41 WST 2000


You can add extra drives later, individually if required, but you may need
to rebuild the array before you can use them depending on how smart the
adaptor is.   A few allow you to just add the extra drives, and take care of
everything internally, most will make you rebuild the array and reload your

In RAID-5 you lose a single disk for parity - so each 18Gb disk you add
after the 3rd will give you another 18Gb.  You need 4x18Gb to get 54Gb of
data (4-1)x18=54.

Steve Baker sbaker at icg.net.au - Integra Consulting Grp http://www.icg.net.au
Open your mind, then look at http://www.nexusmagazine.com

-----Original Message-----
From: Earnshaw, Mike <earnshawm at wa.switch.aust.com>
To: PLUG (E-mail) <plug at plug.linux.org.au>
Date: Thursday, 27 April 2000 9:37
Subject: [plug] Comments on Mylex RAID cards in Linux requested

>I have never implemented any RAID above lvl 1 and never in Linux (past
>experience is NT). We are looking at implementing lvl 5 on our Linux
>fileserver. I tracked down a:
>Mylex acceleRAID 250 for $1200
>and wondered if the list has any experience with this card under Linux.
>Never having implemented lvl 5 before I intended to use 3x18Gb drives (36Gb
>data, 18Gb parity) on the understanding that I can add drives later to
>increase the data size. But in what multiples do I add extra drives? Do I
>have to add drives in increments of 2? So to get 54Gb data, I need 5x18Gb?
>If this is the case given the alarming rate that drives appear to be
>increasing in size, would I be better going for bigger base sizes (36Gb
>instead of 18Gb) to cope with supply problems later.

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