[plug] Comments on Mylex RAID cards in Linux requested

[Steve Baker]

Mike,

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
data.

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.

Regards,
Steve
--
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


>List,
>
>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.
>