RE: RE: I have a clarification

Thanks Dick. But doesn't simply lead to massive fragmentation? Does it unfrag at night while everyone's disconnected?

I can see that if you loaded the arrays with, say, 9G disks, then made all your datafile sizes multiples of that, you'd spread your datafiles onto multiple disks and avoid contention that way, but that kinda defeats the point of spending money on the array...

Cheers,

g

-----Original Message-----
Sent: Wednesday, July 11, 2001 6:02 PM
To: Guy Hammond; Multiple recipients of list ORACLE-L

Guy,

    If I understand the Network Appliance sales droids correctly WAFL stands for
Write Anywhere File Layout. In practice that means that the filer writes your
data to the first available block on the file system irrespective of where the
file's other blocks are. This could be in the same sector of the same disk, or
on a different drive and in a different sector altogether. The point is that
you as a user don't care, it's just one ENORMOUS, and dynamically expandable,
disk drive. It is suppose to be extremely fast (I'm using one right now for NT
files) although I can't say I've seen any kind of difference. One other point
with NetApp is that they accept the data (writing it to flash ram) and lot you
get on with your life, then they write the data to disk and calculate the raid
checksum (or whatever else they call it today) later after your gone.

Dick Goulet

____________________Reply Separator____________________
Author: "Guy Hammond" <guy.hammond_at_avt.co.uk>
Date:       7/11/2001 9:21 AM

Slightly off topic, but would anyone care to comment on the advantages and disadvantages of WAFL versus something like HP AutoRAID?

Thanks,

g

-----Original Message-----
Sent: Wednesday, July 11, 2001 4:36 PM
To: Multiple recipients of list ORACLE-L

BTW, got your book... great job!! You make mention of NetApp and RAID4 in
your book. You say RAID4 is like RAID3 (except it's block level parity) so I
assume it performs like RAID3 which you state is better for DSS but not as
good for OLTP. NetApp claims to have overcome RAID4 performance issues with
their wafl architecture. Any feedback on this?

Waiting for your next book,
Steve Orr

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