Re: Using NetApp Filers for a DWH

That's not it. The RAID-4 has nothing to do with this behavior. The=20 behavior described is symptomatic of a WAFL filesystem with an=20 oversubscribed cache. Since WAFL will never overwrite an existing=20 block, but simply append writes to the next available slot in the free=20=

block list, the tablespace described will effectively be located=20 half-and-half on two different filesystem regions.

If there was enough (read: a lot) of cache in the filer, this problem=20 would be mitigated, since all of the recently modified blocks would be=20=

in cache, but overall this is definitely the worst-case situation for a=20=

Netapp.

Thanks,
Matt

--
Matthew Zito
GridApp Systems
Email: mzito_at_gridapp.com
Cell: 646-220-3551
Phone: 212-358-8211 x 359
http://www.gridapp.com


On Aug 4, 2004, at 7:54 PM, Mogens N=F8rgaard wrote:



> I like the NetApp guys, etc. But it is really RAID-4 (no kidding), so

> perhaps that might explain one or two things? Just guessing...

>

> Mogens

>


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