Results 1 to 7 of 7

Thread: [Transmission] causes heavy file fragmentation

  1. #1

    Default [Transmission] causes heavy file fragmentation

    I have a severe Problem with transmission. It's running as daemon on a headless device on top of a 1,5TB ext3 filesystem. I switched the "preallocation" option on, but the files I download with transmission are heavily fragmented. This already impacts the file system's performance (on that specific files). I can't get read rates more than 5-9MB/s on that files. Does anyone have a tweak to prevent that heavy file fragmentation? (The filesystem has still 800GB of free space)
    An example: The openSUSE-11.3 DVD iso image is fragmented into 194777 "extents"

    Thanks in advance for any useful tipps.

    EDIT: I'm using openSUSE 11.0 which has a 2.6.25er kernel on the affected box. Maybe a ext3 driver problem?!
    Making a copy of the file and then replacing the old one solves all performance problems. (and of course the fragmentation)

  2. #2
    Carlos E. R. NNTP User

    Default Re: [Transmission] causes heavy file fragmentation

    On 2010-09-15 21:36, michivbs wrote:
    >
    > I have a severe Problem with transmission. It's running as daemon on a
    > headless device on top of a 1,5TB ext3 filesystem. I switched the
    > "preallocation" option on, but the files I download with transmission
    > are heavily fragmented. This already impacts the file system's
    > performance (on that specific files). I can't get read rates more than
    > 5-9MB/s on that files. Does anyone have a tweak to prevent that heavy
    > file fragmentation? (The filesystem has still 800GB of free space)
    > An example: The openSUSE-11.3 DVD iso image is fragmented into 194777
    > "extents"


    I wonder if you can make transmission to preallocate each file it will download before downloading
    it. I don't use/know transmission, but if it has that option, use it. If it doesn't have it, check
    to see if it creates "sparse" files, and disable the option.

    Otherwise, change the filesystem. Try XFS, for instance.

    --
    Cheers / Saludos,

    Carlos E. R.
    (from 11.2 x86_64 "Emerald" GM (Elessar))

  3. #3

    Default Re: [Transmission] causes heavy file fragmentation

    I found out, that preallocation in transmission can be set to either 1 or 2. While 2 is the "slow" but complete mode meaning that the whole file is allocated before the download starts. Setting it to 1 does only preallocate parts that are about to be downloaded. That pretty much solved my problem. Maybe i write a script that copies heavily fragmented files top /tmp and back to sanitize my filesystem...

  4. #4

    Default Re: [Transmission] causes heavy file fragmentation

    The copying trick doesn't really work. Most files come back as fragmented as they were. Is there a safe method to defragment an ext3 filesystem without having to create a new one or copy every file to another filesystem?

  5. #5
    Join Date
    Nov 2009
    Location
    West Virginia Sector 13
    Posts
    15,645

    Default Re: [Transmission] causes heavy file fragmentation

    There is for ext4 but I don't know of any for ext3

  6. #6
    Join Date
    Nov 2009
    Location
    West Virginia Sector 13
    Posts
    15,645

    Default Re: [Transmission] causes heavy file fragmentation

    There is a utility for ext4 but I can't find anything for ext3

  7. #7

    Default Re: [Transmission] causes heavy file fragmentation

    Ok i managed to "defrag" the filesystem. I wrote a script that copies all fragmented files to an external harddrive and back. The first try didn't work because i moved the files one by one: Moving one file to /tmp and then immediately back made the filesystem reallocate the same blocks again. (sometimes) I think the thread can be closed...

Posting Permissions

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