home *** CD-ROM | disk | FTP | other *** search
- Newsgroups: comp.sys.mac.system
- Path: sparky!uunet!noc.near.net!news.cs.brandeis.edu!chaos.cs.brandeis.edu!aland
- From: aland@chaos.cs.brandeis.edu (Alan D.)
- Subject: Re: "Get Info" reports different size when file is moved [FAQ?]
- Message-ID: <aland.712509249@chaos.cs.brandeis.edu>
- Sender: news@news.cs.brandeis.edu (USENET News System)
- Reply-To: aland@cs.brandeis.edu
- Organization: As little as possible
- References: <1992Jul30.141956.13014@eplrx7.es.duPont.com>
- Distribution: usa
- Date: Thu, 30 Jul 1992 15:14:09 GMT
- Lines: 80
-
- milbouma@esvax.dnet.dupont.com writes:
-
- >This subject has come up before, I think, but I need a refresher, prompted by a
- >question from a curious fellow Mac support person.
-
- Is this in the FAQ list? Rusty? *grin*
-
- >How does the Finder and Get Info calculate/report the amount of disk used by a
- >document?
-
- The Finder and Get Info are correct... The file is 2048 bytes long.
- (because a Word file has some overhead to it, beyond the actual text
- contents).
-
- >Mac with system 7 is used to create an MS-Word file (with one word in it).
- >Get Info reports file is: 3K (2048 bytes used)
-
- This hard drive has either a 1.5 or a 3K block size (minimum amount of
- disk space a file can take up).
-
- >Document is transferred to floppy.
- >Get Info reports this copy is: 2K (2048 bytes used)
-
- A floppy has either .5K or 1K blocks; I think .5 but I'm not positive;
- therefore this is correct (eg. not wasteful).
-
- >Floppy put into system 6 Mac, Get Info shows same as previous (2K)
-
- None of this is system-dependent...
-
- >Document copied to system 6 Mac's hard drive (a large drive ~1.2GB)
-
- >Get Info reports this copy is: 17K (2048 bytes used)
-
- The block size on the 1.2GB drive must therefore be 17K.
-
- >Why would 17K of disk space be needed to store a 2K document. I know there is
- >some overhead with format info, directory info and pointers, but
- >a 17:2 ratio? Would sectors on a large capacity drive be much larger (some
- >minimum greater than 2K)? Or does it relate to a difference in the way system
- >6 and system 7 handle these things?
-
- There are, in the current (September) issue of MacUser magazine, a few
- "common threads" in the text. One is this name that keeps popping up,
- 'Adam Engst'. In the letters, "Shareware Top Hits" article, etc...
- The other is that you should partition large hard drives ('large'
- being greater than 31.5 Meg) in order to efficiently allocate space.
- At least, for drives on which you expect to store small documents.
-
- Basically, there are a limited number of blocks which can be allocated
- on a volume (I believe there are 32768 +/- 2), and if you have more
- than that number of blocks, the formatter increases the block size so
- you don't exceed that number. Therefore, if you have a need for
- storing many small files (around 1-2K), you should (ideally) make it a
- 30 meg partition (which gets you a block size of 1K).
-
- For larger files, you can have a larger partition, since the
- approximate percentage of wasted space is that much smaller... If
- this makes any sense.
-
- So, you should partition your 1.2 gigabyte drive into multiple volumes
- (using LaCie's SilverLining, FWB's Hard Drive Toolkit, or Drive7 (the
- company which makes this one escapes me...)). These are the most
- 'common' and fully-featured disk formatting/partitioning programs.
-
- One thing you should be aware of (and avoid) is that you want to
- partition the drive using "hard partitions" (true SCSI partitions)
- rather than "soft partitions" (large files which the Mac OS is fooled
- into thinking are hard partitions). Hard partitioning allows you to
- mount the volumes when you boot w/out extensions & if you move the
- hard drive to another Mac; they can be used as boot drives; if one
- crashes, the others will usually be fine. With soft partitioning, if
- the "real" SCSI partition fails, all your soft partitions are goners
- as well.
-
- Well, there's my treatise on 'mass media block sizes' and
- partitioning... I hope you enjoyed it. Inaccuracies, etc. should be
- sent to me, so I can correct my mistakes...
-
- -=Alan
-