Basic File System question...
Results 1 to 3 of 3

Thread: Basic File System question...

  1. #1
    Senior Member
    Join Date
    Oct 2005
    Posts
    106

    Basic File System question...

    OK, so I have been studying the I-node based file systems recently (largely the Minix file system, and the Ext2 file system); I understand that the partition is divided into block groups, and all that jazz, but what I don't understand is this: is there a limit, like some parameter, that constrains the maximum number of block groups?

    I mean, suppose we had an ideal computer with 1 Yottabyte of space (or 2 to the 80th bytes). If we had the block size be 2^12 bytes (4 KB), there are 2^68 blocks. Here's the problem: an unsigned long long is capable of a maximum value of 2^64. Wouldn't there be 2^68 - 2^64 blocks that won't be accessible? Granted that this is so large that it wouldn't matter, but it wouldn't be that efficient (well, 2^64 over 2^68 = 0.000244141 = 0.024%, which is pretty lousy).

    Am I approaching this the wrong way, or does the number of block groups not matter?
    "The Texan turned out to be good-natured, generous and likeable. In three days no one could stand him." Catch 22 by Joseph Heller.

    Buddies? I have no buddies...


    Give the BSD daemon some love (proud FreeBSD user)

  2. #2
    Just Another Geek
    Join Date
    Jul 2002
    Location
    Rotterdam, Netherlands
    Posts
    3,401
    IIRC most filesystems have an upper limit. They're size restricted. When bigger drives get available new filesystems must be created to allow for those sizes.

    FreeBSD's UFS has a size limit of 2TB (2^32 * 512 bytes), UFS2 allows for 8ZB (ZetaByte; 2^64 * 512 bytes).

    http://www.freebsd.org/projects/bigdisk/index.html
    Last edited by SirDice; February 7th, 2007 at 11:01 AM.
    Oliver's Law:
    Experience is something you don't get until just after you need it.

  3. #3
    Senior Member
    Join Date
    Oct 2005
    Posts
    106

    Thumbs up

    Interesting, thanks! That really answered all of my questions, and the ones that I've been thinking about since this morning.

    I greatly appreciate it!
    "The Texan turned out to be good-natured, generous and likeable. In three days no one could stand him." Catch 22 by Joseph Heller.

    Buddies? I have no buddies...


    Give the BSD daemon some love (proud FreeBSD user)

Similar Threads

  1. Windows Error Messages
    By cheyenne1212 in forum Miscellaneous Security Discussions
    Replies: 7
    Last Post: February 1st, 2012, 02:51 PM
  2. Trojans - Ports
    By GbinaryR in forum AntiVirus Discussions
    Replies: 11
    Last Post: October 30th, 2008, 10:33 AM
  3. Port List
    By ThePreacher in forum Miscellaneous Security Discussions
    Replies: 17
    Last Post: December 14th, 2006, 09:37 PM
  4. Test Your General Linux Knowledge
    By smirc in forum AntiOnline's General Chit Chat
    Replies: 6
    Last Post: May 13th, 2002, 05:35 PM
  5. Test Your Knowledge of Redhat?
    By smirc in forum AntiOnline's General Chit Chat
    Replies: 3
    Last Post: May 13th, 2002, 04:24 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •