From: SMTP%"dbeaver@exchange.microsoft.com" 12-DEC-1997 17:33:54.07 To: "'Jamey Kirby'" , Martin von Loewis , Thomas_hildebrandt@europe.mcd.mot.com CC: ntdev@atria.com, ntfsd@atria.com Subj: RE: [ntfsd] Re: [ntdev] huge files Return-Path: owner-ntfsd@atria.com Received: by arisia.gce.com (UCX V4.1-12C, OpenVMS V7.1 VAX); Fri, 12 Dec 1997 17:32:49 -0500 Received: from gw.atria.com (gw.atria.com [192.88.237.2]) by mercury.mv.net (8.8.8/mem-971025) with SMTP id RAA28978 for ; Fri, 12 Dec 1997 17:21:05 -0500 (EST) Received: by gw.atria.com id Fri, 12 Dec 1997 14:16:03 -0500 Received: from doggate.exchange.microsoft.com by gw.atria.com id Fri, 12 Dec 1997 14:15:56 -0500 Received: by DOGGATE with Internet Mail Service (5.5.1960.3) id ; Fri, 12 Dec 1997 11:20:09 -0800 Message-ID: <0A684133865BCF118F0E08002BE7ADAC016727F0@DABONE> From: "David Beaver (Exchange)" To: "'Jamey Kirby'" , Martin von Loewis , Thomas_hildebrandt@europe.mcd.mot.com Cc: ntdev@atria.com, ntfsd@atria.com Subject: RE: [ntfsd] Re: [ntdev] huge files Date: Fri, 12 Dec 1997 11:19:57 -0800 X-Mailer: Internet Mail Service (5.5.1960.3) Sender: owner-ntfsd@atria.com Precedence: bulk X-Majordomo-Taboo: ntfsd Well, yes and no. "Sparse file support" is in the NTFS ODS but not supported in the OS; in other words, you could build a sparse file if only the OS had some way of letting you. With NT5, true sparse file support is expected in the OS (there are some FSCTLs that are doc'ed in the beta 1 PDK CD, look for sparse), so you'll be able to create sparse files and only have the data actually resident in them on the disk. The fact that you see what looks like sparse files when you compress them is strictly an artifact of the compression; removing zero-filled runs is the most effective and lowest cost thing you can do during compression. Compression goes much further than this in creating compressed files; this is just the first step, and it looks a lot like sparse file support. The real sparse file support never creates those runs of zeros, so the compression stuff doesn't have to remove them. .............dave > -----Original Message----- > From: Jamey Kirby [SMTP:jkirby@cts.com] > Sent: Friday, December 12, 1997 5:21 AM > To: Martin von Loewis; Thomas_hildebrandt@europe.mcd.mot.com > Cc: ntdev@atria.com; ntfsd@atria.com > Subject: Re: [ntfsd] Re: [ntdev] huge files > > That is authoratative enough for me. Thanks Martin. > > Jamey Kirby > Senior Partner > Magnuson, Kirby & Associates, LLC. > jkirby@cts.com > http://www.mkallc.com > -----Original Message----- > From: Martin von Loewis > To: Thomas_hildebrandt@europe.mcd.mot.com > > Cc: ntdev@atria.com ; ntfsd@atria.com > Date: Friday, December 12, 1997 4:57 AM > Subject: Re: [ntfsd] Re: [ntdev] huge files > > > >> Hmmmm... I think the point is still not very clear. According to > Custers > book, it seems that NTFS file compression is exactly what is done by > sparse > file allocation in other operating system environments, only it is done on > demand and *after* the file has been created, not automatically. If James' > information about 5.0 is right, I would consider it a big step forward > towards conserving still valuable (and sometimes still expensive) disk > space. > > > >There is no need to guess when you can observe :-) In NT 4, sparse > >runs are created when the file is compressed. For uncompressed files, > >I never observed the usage of sparse runs. > > > >Please note that this still fits your definition of 'supporting sparse > >files'. If the directory is marked as compressed, new files will > >automatically be compressed as well, and sparse runs are introduced > >as soon as you write beyond the end of the file. > > > >For NT 5, I have no information. > > > >Regards, > >Martin > > - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > >[ To unsubscribe, send email to ntfsd-request@atria.com with body > >UNSUBSCRIBE (the subject is ignored). ] > > > > - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > [ To unsubscribe, send email to ntfsd-request@atria.com with body > UNSUBSCRIBE (the subject is ignored). ] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - [ To unsubscribe, send email to ntfsd-request@atria.com with body UNSUBSCRIBE (the subject is ignored). ]