Re: [Veritas-bu] NBU 5.1: Disk staging causing heavy fragmentation
2008-02-20 12:32:55
Hmmmm.... Not sure its common in NTFS though, however the
older file systems FAT & FAT32 definetely would play a part in
this.
Saying that, if users continually delete files from the
same volume and they are restored from tape, would this increase
fragmentation?
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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