Re: RAID 1 or 5 ?

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Article #463

#463

From: prostorage
Date: Sat, 25 Sep 1999 00:00

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In article <37EB92A6.8579E99A@ultrafast.net.no.sp.am>, 
RAIDER@ultrafast.net.no.sp.am says...
>Jim, let it be known that a hot spare drive in a RAID 5 setup does 
>NOTHING to protect from a failure of more than one drive at a time. What
>it does do, however, it minimizes MTTR (Mean Time To Repair) because
>most raid controllers will automatically initiate a rebuild of a failed 
>drive onto a hot spare. Should another disk fail while the rebuild is 
>still in progress - the RAID set and all the data on it will be lost.
>RAIDER
>
>Jim Pappe wrote:
>> 
>> with Raid 5 plus hot spare - 2 drive can fail ..
>> www.raidexpert.com
>> 

RAIDER is correct
a second "warm" or "hot" spare would do nothing to save you if 2 
drives went down at the same time

the only way that i know of to live through the failure of 2 drives
simultaneously is to have 2 separate RAID 5's running as the 
mirrored drives in a RAID 1 (& we've done this)

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<7nl85m$3nn$1@newton.pacific.net.sg> <37E1425E.9F4D1F3B@t-online.de> <937569107.3977.0.nnrp-11.9e98b72c@news.demon.co.uk> <37e660eb.12904299@news.earthlink.net> <7sehd5$80a@journal.concentric.net> <37EB92A6.8579E99A@ultrafast.net.no.sp.am>

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From: prostorage@earthlink.net (prostorage)
Subject: Re: RAID 1 or 5 ?
Date: 1999/09/25
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