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RE: DBA-Database Storage using Net Appliance

From: Rich Holland <holland_at_guidancetech.com>
Date: Thu, 14 Feb 2002 15:14:15 -0800
Message-ID: <F001.00410570.20020214144129@fatcity.com>

NetApp Filers use WAFL (Write Anywhere File Layout. WAFL is similar to other Unix filesystems like FFS in that it's a block-based file system using inodes to describe files. It uses 4K blocks with no fragmentation. Each WAFL inode has 16 block pointers that point to data blocks. Unlike FFS, all the block pointers in a WAFL inode refer to blocks at the same level. For files smaller than 64K the 16 inode blocks point to data blocks. Larger files use indirect pointers (inode blocks point to other inode blocks). Very large files use double inderect pointers (inode -> inode -> inode -> data). Very small files use the inode blocks themselves instead of the block pointers.

WAFL stores file system metadata in files (inode file, block-map file, and inode-map file. Keeping this data in files allows the Filer to write the data anywhere on the disk (rather than to a "superblock" like FFS), which is where the WAFL name comes from. This also allows the Filer to schedule writes to the same RAID stripe to avoid the 4-1 write penalty you usually incur when you update a single block in a stripe.

Other nice features from a sysadmin point of view are the fact that the Filer will automatically increase the size of your filesystem when you add another disk, and the use of snapshots. Snapshots are really cool if you haven't seen them before. Basically from the point in time the snapshot is taken, the filesystem has to write all new data (including meta-data) to new locations on the disk instead of overwriting the old data. If WAFL used a superblock like FFS, this wouldn't be possible. If data is changed, the Filer uses a copy-on-write technique to keep the old block avialable for any snapshots which reference it.

I've never used a Filer for Oracle applications; I've only used EMC due to the size & availability requirements of the implementations I've worked on, but I know it's been done by others.

If you poke around at http://www.netapp.com/ you can probably find Dave Hitz' original white papers on WAFL and the design of the filer (formerly called FAServer) if this sort of thing interests you.

Rich
> -----Original Message-----
> From: root_at_fatcity.com [mailto:root_at_fatcity.com] On Behalf Of
Berkmeyer,
> Sue
> Sent: Thursday, February 14, 2002 10:29 AM
> To: Multiple recipients of list ORACLE-L
> Subject: DBA-Database Storage using Net Appliance
>
> Hi Everyone,
>
> I am getting pressure from the system guys to use a Net
Appliance
> filer for Oracle Applications databases. I currently have the Apps
> Release
> 11.0.3 production database on a Sun E4500, 4G RAM, 6CPU_at_400Mhz and a
Sun
> storage array with a mix of 4 and 9G drives. The production datafiles
are
> on Raid 0+1. The production software is mirrored only. Sequential
files
> are not "raided". I have gone out to the Net Appliance web site and
have
> download papers about how to implement Oracle on the filer. I would
like
> to
> hear from real users rather than the vendor about how this works.
> Therefore
> I am curious to find out anyone's experience with this storage
technology
> -
> good or bad. If anyone has any insights about the Net Appliance
> technology
> itself i.e. raid level, etc. that would be great too. We are also
> considering a new Sun direct attached storage solution. Thanks for
your
> time.
>
> National Renewable Energy Laboratory
> Sue Ellen Berkmeyer
> Database Administrator
> Phone: 303-275-4143
> Fax: 303-275-3603
> E-mail: sue_berkmeyer_at_nrel.gov
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Berkmeyer, Sue
> INET: Sue_Berkmeyer_at_nrel.gov
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Rich Holland
  INET: holland_at_guidancetech.com

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San Diego, California        -- Public Internet access / Mailing Lists
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Received on Thu Feb 14 2002 - 17:14:15 CST

Original text of this message

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