The snapshot folding happens in WAFL of course, but the trigger to cause a file to be scanned happens based on CIFS requests. If an NFS client overwrites a file with identical data it will result in new allocations. If a CIFS client does that when the folding option is "on" it will not result in new allocations if the old blocks are in the last snapshot. This works even if the data is written to a temp file which is subsequently renamed to the original file, as Windows applications typically do.
At some point we plan to add support for NFS, and/or to add a way to manually force a folding scan on a directory, etc. If people are interested in this let me know so I can add your comments to the feature request.
Mark Muhlestein -- Network Appliance Engineering
-----Original Message----- From: Dirk Schmiedt [mailto:Dirk.Schmiedt@munich.netsurf.de] Sent: Wednesday, August 07, 2002 10:05 AM To: stefan.holzwarth@zentrale.adac.de Cc: toasters@mathworks.com Subject: Re: Snapshot storage
stefan.holzwarth@zentrale.adac.de wrote:
...
After looking around i found some users using their quota
for doing backups
to our filer. That backups were deleted after 2 weeks and replaced by new backups. This led to a large amount of data invisible to the quota system, but wasting a lot of snapstorage.
How can i deal with that situation and especialy: how to
find users/qtrees
with a lot of changed data?
Hello Stefan
- As the others already stated: For (not just ... :-) ) CIFS
there is this new filefolding option. If you take a closer look at the "options" manpage explaining this new ONTAP 6.2 feature you can detect, that it will work on any file getting closed without making any difference wether it is a CIFS or NFS file close => It works for NFS, too. It was just named, CIFS option because there it is needed by this "document.xxx gets renamed to document.bak and then write document.xxx again" behaviour of MS-Applications... You usually don't need it if you have NFS Clients .... and ... if you are not having users that explicitely rewrite their data over and over again .. like your users do. :-(
Maybe NetApp can/will? change this option to a wafl-option? cifs -> wafl.snapshot_file_folding.enable
Muhlestein, Mark wrote:
The snapshot folding happens in WAFL of course, but the trigger to cause a file to be scanned happens based on CIFS requests. If an NFS client overwrites a file with identical data it will result in new allocations. If a CIFS client does that when the folding option is "on" it will not result in new allocations if the old blocks are in the last snapshot. This works even if the data is written to a temp file which is subsequently renamed to the original file, as Windows applications typically do.
At some point we plan to add support for NFS, and/or to add a way to manually force a folding scan on a directory, etc. If people are interested in this let me know so I can add your comments to the feature request.
Mark Muhlestein -- Network Appliance Engineering
Hello Mark
You are right. File folding currenty really is just CIFS not NFS. I read the manpage too fast. Sorry.
I think, this would be a cool feature for NFS-files, too. Especially for those "I backup my local PCs files to the filer" guys ... One more request for enhancement: Due to the performance impact of file folding (ff) ...: How about moving this ff option from a system wide range to a volume based option? Therefore I could create one volume for NFS-Backups and CIFS users with the low(er) ff performance and one without ff for the other NFS-clients...
Just my 2 cents.
Best regards! Dirk
On Thu, Aug 08, 2002 at 12:20:20AM +0200, Dirk Schmiedt wrote:
At some point we plan to add support for NFS, and/or to add a way to manually force a folding scan on a directory, etc. If people are interested in this let me know so I can add your comments to the feature request.
How about moving this ff option from a system wide range to a volume based option?
Hey, don't shorten their vision, they wanted to do it per directory ;)
(I'd like to have it per qtree)
p.
-
Dirk Schmiedt -
Muhlestein, Mark -
Piotr KUCHARSKI