Re: Disk Mangement Advice
From: Eugene Taylor (ewtaylor2001_at_fake.com)
Date: 01/06/05
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Date: Thu, 6 Jan 2005 14:03:00 -0500
Actually RAID 0 is the fastest with no parity. Of course this does not give
you any fault tolerance. The other speeds depends on a lot of issues what
kind of RAID card you are using and how much memory that card has. The good
thing about RAID cards is the machine writes it to memory then the memory
writes it to disk, while the cpu is off doing other things. Most files you
write will not be much greater than 128 meg. So either RAID would be faster
than just writing it to a disk... of course this all depends on what kind of
bus you are using (ide Vs scsi etc...) and what speed drives you are using.
"Phillip Windell" <@.> wrote in message
news:%236gLlyB9EHA.2180@TK2MSFTNGP12.phx.gbl...
> "Phillip Renouf" <PhillipRenouf@discussions.microsoft.com> wrote in
message
> news:2DD332DE-C485-496F-A186-B6A0C0F87AB3@microsoft.com...
> > Writing to a RAID5 set is a much bigger performance hit than writing to
a
> > RAID1 set. In a RAID1 set you are only writing to 2 drives, but in a
RAID5
> > set you are writing to 3+ drives and it also has to calculate the parity
> > information.
> >
> > Also, the n-1 does not denote that one drive holds the parity data:
> > effectively with a RAID5 set the available drive space is effectively
> equal
> > to n-1. The parity data is actually spread across all the drives.
>
> No, the fact that it is 3 drives (or 4 or 5) doesn't not make it slower.
In
> fact it is faster because it writes to all of them at same time and does
not
> have to write the data twice. The data is also evenly divided across the
> drives so that only a portion of the data need to be writen to each one.
> There is a slight time loss for the Parity but the "cost" of this
negligable
> and often exaggerated and is nearly compensated for by the faster
> writetimes. There is also two RAID5's,...there is RAID5 with Parity and
> Raid5 without Parity (Stripped Set). The RAID5 without Parity is the
fastest
> RAID of them all.
>
> RAID1 is slower because and entire copy of the data goes to the second
drive
> so the data being completely written twice in its entirety creates a
"cost".
>
> --
>
> Phillip Windell [MCP, MVP, CCNA]
> www.wandtv.com
>
>
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