[ale] "Cost" of raid?

[Jeff Hubbs]

Just from what you're saying and presuming that you're going to do
kernel RAID, You might want to lay off the RAID 5 if you're very
write-dependent.  The kernel has to generate parity for writes, and if
your machien is busy "doing some calculations" then you might feel some
pain from that.  

If you can bring more drives to bear, however, you can split up your
disk duties and set up some RAID 0+1 AND some RAID 5.

- Jeff


On Thu, 2002-09-26 at 16:29, Robert L. Harris wrote:
> 
> 
> Collecting data, doing some calculations on that data then pushing it
> and the output to another machine.
> 
> Thus spake Jeff Hubbs (hbbs at attbi.com):
> 
> > From: Jeff Hubbs <hbbs at attbi.com>
> > To: "Robert L. Harris" <Robert.L.Harris at rdlg.net>
> > Cc: Atlanta Linux Enthusiasts <ale at ale.org>
> > X-Mailer: Evolution/1.0.2-5mdk 
> > Date: 26 Sep 2002 16:07:07 -0400
> > Subject: Re: [ale] "Cost" of raid?
> > 
> > Robert -
> > 
> > What's the machine going to be doing?
> > 
> > - Jeff
> > 
> > 
> > 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);'
> > > 
> > > 
> > > ---
> > > This message has been sent through the ALE general discussion list.
> > > See http://www.ale.org/mailing-lists.shtml for more info. Problems should be 
> > > sent to listmaster at ale dot org.
> > > 
> > 
> > 
> > 
> > ---
> > This message has been sent through the ALE general discussion list.
> > See http://www.ale.org/mailing-lists.shtml for more info. Problems should be 
> > sent to listmaster at ale dot org.
> 
> 
> 
> :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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