Date: Thu, 26 Apr 2007 11:16:00 -0500 From: "GARRISON, TRAVIS J." <garrisot@otc.edu> To: <freebsd-questions@freebsd.org> Subject: RE: Single Instance Service Message-ID: <06D1B6D4926222458F803D0D3EDCCB7E01D0A790@EXM1.otc.edu> In-Reply-To: <200704260635.l3Q6ZZhL090019@banyan.cs.ait.ac.th>
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> -----Original Message----- > From: owner-freebsd-questions@freebsd.org [mailto:owner-freebsd- > questions@freebsd.org] On Behalf Of Olivier Nicole > Sent: Thursday, April 26, 2007 1:36 AM > To: m.seaman@infracaninophile.co.uk > Cc: GARRISON, TRAVIS J.; freebsd-questions@freebsd.org > Subject: Re: Single Instance Service >=20 > > Sure it is. You will need to write a small shell script to scan > > your disk volume and calculate the checksum of each file. When > > ever it finds a duplicated checksum, then it copies the file into > > the central store and replaces the on-disk copies with symbolic > > links. That's fairly trivial to write. >=20 > Beside, what should be the behaviour when one wishes to modify his own > copy of a document? How does Single Instance acts in that case? >=20 > If you establish a link, there is only one version of the file, once > and forever (unless you go and unlink it manually), so when one > modifies the file, modification applies for everyone. >=20 > Olivier [GARRISON, TRAVIS J.]=20 I know with Windows Storage Server, if a user modifies the file, it will then create the user their own copy of the file. This happens automatically. Exchange Server is another example of this type of storage. When someone sends an attachment to several people, the server saved one copy of the file. I am currently managing 7TB worth of data with roughly 1 to 2TB of duplicate files. This gets fairly expensive with a fiber channel san backend. I know it can be done in the windows world automatically, just wondered if it could be done automatically in the Unix world also.
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