[hfs-user] HFS Maximum Image Size

Entwicklung entwicklung@whengenibk.de
Tue, 23 Apr 2002 07:37:22 +0200


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Hello,
        I made a mistake . I had thought that drNumAlBlocks and =
drAlBlkSize in the MDB were both of type UInt16 but drAlBlkSize happens =
to be of size 4Bytes - I didn't see that.

Thanks!
-Nandini



----- Original Message -----=20
  From: Mark Day=20
  To: Entwicklung=20
  Cc: hfs-user@lists.mars.org=20
  Sent: Monday, April 22, 2002 10:35 PM
  Subject: Re: [hfs-user] HFS Maximum Image Size


  The maximum file size on HFS volumes is 2GB-1 (the maximum value in a =
signed 32-bit integer). See struct HFSCatalogFile.

  The maximum volume size is theoretically just under 256TB (actually, =
65535 allocation blocks * (4G-512) bytes per allocation block). The =
allocation block size is an unsigned 32-bit integer, but must be a =
multiple of 512. I don't know of any implementation that supports HFS =
volumes 2TB or larger; some versions have much smaller limits (eg., 2GB =
or 4GB). Many implementations use 32-bit integers (signed or unsigned) =
for offsets into the volume, or as block numbers (assuming 512 bytes per =
block).

  -Mark

  On Sunday, April 21, 2002, at 07:44 AM, Entwicklung wrote:


                       The maximum size of an HFS-volume seems to be =
65535*65535 =3D 3.99 GB. (since the respective fields in the MDB are =
UInt16's). Does this mean that to store a file of size 4.7GB I would =
have to necessarily go in for HFS+ or is this possible with HFS somehow =
?


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<DIV><FONT face=3DArial size=3D2>Hello,</FONT></DIV>
<DIV><FONT face=3DArial =
size=3D2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; I made a=20
mistake . I had thought that drNumAlBlocks and drAlBlkSize in the MDB =
were both=20
of type UInt16 but drAlBlkSize happens to be of size 4Bytes - I didn't =
see=20
that.</FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>Thanks!</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>-Nandini</FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV>----- Original Message ----- </DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: =
0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
  <DIV=20
  style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
  <A href=3D"mailto:mday@apple.com" title=3Dmday@apple.com>Mark Day</A> =
</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A=20
  href=3D"mailto:entwicklung@whengenibk.de"=20
  title=3Dentwicklung@whengenibk.de>Entwicklung</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Cc:</B> <A=20
  href=3D"mailto:hfs-user@lists.mars.org"=20
  title=3Dhfs-user@lists.mars.org>hfs-user@lists.mars.org</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Monday, April 22, 2002 =
10:35=20
  PM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: [hfs-user] HFS =
Maximum Image=20
  Size</DIV>
  <DIV><BR></DIV>The maximum file size on HFS volumes is 2GB-1 (the =
maximum=20
  value in a signed 32-bit integer). See struct =
HFSCatalogFile.<BR><BR>The=20
  maximum volume size is theoretically just under 256TB (actually, 65535 =

  allocation blocks * (4G-512) bytes per allocation block). The =
allocation block=20
  size is an unsigned 32-bit integer, but must be a multiple of 512. I =
don't=20
  know of any implementation that supports HFS volumes 2TB or larger; =
some=20
  versions have much smaller limits (eg., 2GB or 4GB). Many =
implementations use=20
  32-bit integers (signed or unsigned) for offsets into the volume, or =
as block=20
  numbers (assuming 512 bytes per block).<BR><BR>-Mark<BR><BR>On Sunday, =
April=20
  21, 2002, at 07:44 AM, Entwicklung wrote:<BR><BR>
  <BLOCKQUOTE><?fontfamily><?param =
Arial><?smaller>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb=
sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;=20
    The maximum size of an HFS-volume seems to be 65535*65535 =3D 3.99 =
GB. (since=20
    the respective fields in the MDB are UInt16's). Does this mean that =
to store=20
    a&nbsp;file of size&nbsp;4.7GB I would have to necessarily go in for =
HFS+ or=20
    is this possible with HFS&nbsp;somehow=20
  ?<?/smaller><?/fontfamily><BR></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>

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