Re: [Veritas-bu] NBU 5.1: Disk staging causing heavy fragmentation
2008-02-20 12:14:21
I still think that MS’s “undelete” feature
plays a part in this. When data is “deleted” in Windows, NTFS marks
blocks to be released without actually erasing them. Rather than reusing
released blocks, NTFS prefers new, unused blocks, which leads to fragmentation.
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of WEAVER,
Simon (external)
Sent: Wednesday, February 20, 2008 11:21 AM
To: Tony T.; veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] NBU 5.1: Disk staging causing heavy
fragmentation
Today's NTFS handles fragmentation
alot better - in fact, FAT and FAT32 were really the main file systems that
would always get fragmented. That is not to say NTFS is not immune to the
fragmentation that people may experience, but there are ways around to minimise
it even more.
Depending on the volume itself,
and its intention is the key to keeping fragmentation down. When you format a
volume you get the option of a "cluster" size. But you must be aware
of what the volume itself will be storing. (for example, large files, or
millions of small files).
By default, when formatting,
Windows keeps a "default" setting in place. Choosing a smaller
cluster variable will waste less disk space but likely to cause fragmentation.
Likewise, a larger cluster
variable will cause less fragmentation but waste space. further details can be
found in the online help of Win2k3, XP, 2000, ect !
Not to put my foot in it, but I am
sure other systems suffer, but maybe its a NTFS thing ;-)
Simon.
From:
veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Tony T.
Sent: Wednesday, February 20, 2008 4:07 PM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] NBU 5.1: Disk staging causing heavy
fragmentation
It's NTFS and you're creating and deleting a lot of files on the volume so of
course it will fragment. Either defragment the volume or set the minimum
threshold lower so that more files get deleted when the cleanup process runs to
reduce the fragmentation.
.../Ed
--
Ed Wilts, Mounds View, MN, USA
mailto:ewilts AT ewilts DOT org
Thanks for the info guys.
It sounds like fragmentation is just a given when it comes to backing up
to disk? I understand that, as seeing it explained does make sense.
I have been looking for some of this "well documented" information
and have come up empty. Searching for fragmentation on Symantecs site is
like a journey through the looking glass. I will keep looking, but if
anyone has any links to a white paper or something it would be much
appreciated.
Also, when you say "set the minimum threshold lower so that more files get
deleted..." This confused me; I mean, isn't the fragmentation being
caused by so many file creation/deletions? Wouldn't increasing the amount
of files being deleted also increase the fragmentation?
Or did I misread that?
Thanks again for the info,
T.
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