Journaling: Yes or No?

Discussion in 'General Mac Discussion' started by amc382, Jan 24, 2004.

  1. amc382 macrumors regular

    Nov 4, 2003
    Which would you recommend:

    Journaling enabled or journaling disabled?

    I've heard that enabling it slows things down alot? What are the advantages of enabling it?
  2. jxyama macrumors 68040


    Apr 3, 2003

    it will make your start up time much faster. and i haven't noticed any general slow downs otherwise.
  3. idkew macrumors 68020


    Sep 26, 2001
    where the concrete to dirt ratio is better
  4. Flickta macrumors 6502

    Nov 20, 2002
    Born in USSR
    Go on! Enable it!

    It didn't save my data, though. Sad story happened two days ago.

    Didn't wake up - reboot - disk unrecoverable - intialisation - clean install.
  5. baby duck monge macrumors 68000

    baby duck monge

    Feb 16, 2003
    Memphis, TN
    i have heard a pretty good amount of talk about journaling as this wonderful feature in 10.3, but i am ashamed to say that i don't really understand what it does or what services it provides. could someone please enlighten me?

    also, do your suggestions for enabling it apply even on slower HDs?

    sorry to kinda hijack, and thanks for any info.
  6. jxyama macrumors 68040


    Apr 3, 2003
    i know very little about journaling as well, so i'd also welcome more thorough description.

    anyway, afaik, journaling basically keeps track of each and every file that's on the HD. this makes file system checks mostly unnecessary, thus making the start up faster...
  7. Marble macrumors 6502a


    May 13, 2003
    Tucson, AZ
    Journaling creates noticeable lag when moving any data around in the filesystem on my 4200rpm Powerbook drive. It makes no noticeable difference on my 7200rpm external firewire drive.
  8. Westside guy macrumors 601

    Westside guy

    Oct 15, 2003
    The soggy side of the Pacific NW
    In short, journaling keeps track of diffs on your filesystem. When you initiate a disk write, the journaling subsystem notes the current state of the bits about to be overwritten and the changes to be made. Then the actual disk write happens.

    If something happens before the actual write occurs, the journal has the record of the change - the journal is checked upon reboot and the changes are written. This mostly (but not completely) eliminates the possibility of disk corruption.

    It does slow things down a little, but for most disk writes (editing files etc.) very little on the disk actually changes. The journal only need to track the changes, so it's not going to slow things down too much. Also, most journaling systems have a cache and write the file updates in bulk to the disk every X seconds (I know the ext3 filesystem uses X=5 by default; don't know much of anything about HFS+ journaling yet). Note that the journal log writes are not cached - it's the file updates themselves that are.

    Edit: I couldn't find an article specific to HFS+ journaling, but here's one that talks about various Linux filesystems:

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