[ale] "Cost" of raid?

[Ryan Matteson]

If you do not have a hardware RAID controller, and your application does
a lot of I/O, look out. I have worked with SDS and VxVM (Sorry no Linux
VM) software RAID5 solutions. When a drive fails, each read requires the
Volume Manager to recreate the data from the parity and the existing
data (if the column in question contains data). To assess your
requirements, we would need more information on the application I/O
patterns, and whether the application was read or write happy.

- Ryan


On Thu, 2002-09-26 at 15:58, Robert L. Harris wrote:
> 
> 
> 
>   I'm effectively "pricing" raid for a system on our network.  Currently
> they have 4x18Gig disks, Raid 0 giving them 72Gigs available.  I've done
> a breakdown of how much disk is available, what will be the effects on
> space and redundance.  
> 
>   One question hit me I'm not sure how to answer though.  How much
> slower is Raid 5 than a Raid 0+1?  Will it be noticable?  This system is
> very IO intensive with an average load around 0.8.
> 
>   The box is a dual-P3-850 with 4x18Gig SCSI Cheetas.
> 
> 
> :wq!
> ---------------------------------------------------------------------------
> Robert L. Harris                
>                                
> DISCLAIMER:
>       These are MY OPINIONS ALONE.  I speak for no-one else.
> FYI:
>  perl -e 'print $i=pack(c5,(41*2),sqrt(7056),(unpack(c,H)-2),oct(115),10);'
> 
> 
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-- 
Ryan Matteson - UNIX Administrator
GPG ID: 782C2F4B Ryan Matteson (Matty) <matty91 at bellsouth.net>
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