Re: [Plug] soft RAID

[Andrew Libby <alibby@voicenet.com>]

Yes, the A5000 is a dumb array.  I've seen people do 
RAID5 with it, and other dumb SSA (Sparc Storage Array) devices. 
One example was Drexel university.  They used SDS (Solstice Disk
Suite) to Raid5 their mail partitions /var/mail.  Once they
grew to about 15K users though, this became too much overhead
for the E4000 server.  Since then they've gone from using Raid 0+1
on /var/mail to migrating mail to a separate server, running SIMS,
and I'm not sure what the RAID setup is, though I'd presume it's
0+1.

Essentially, host base RAID5 can be attractive when
you've got a high read/ low write situation.  The overhead
of RAID5 is introduced when writes take place. In a read 
intensive environment RAID5 can be better then RAID0, but is 
rarely more attractive 0+1 (save the situation when disk space
is at a premium).

my $0.02. 
Thoughts are welcome, but be easy on me.

Andy


On Tue, Aug 10, 1999 at 10:26:56AM -0400, John Nolan wrote:
> 
> Isn't this analogous to the whole Winmodem question?
> It's possible to move the processing from the controller
> board to the main CPU, but this is generally a bad idea because
> it takes up CPU time and defeats device abstraction. 
> 
> Isn't there some line of Sun RAID products which uses 
> software RAID 5 ?  I think I remember some users complaining
> about it, but I've forgotton which product it is.  
> It's not the A5000's, is it? 
> 
> 

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