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RAID-0 de-frag

By Sparky Joe
Jul 19, 2006
  1. I just set up a RAID-0 set yesterday, and throughout my research on how to do it I thought I saw something that said striped sets become fragmented quickly. Is this true?
    If so, how often should I be de-fragging?
    And would anyone recommend utilities that de-frag the drive(s) while the system is at idle(think I saw this sort of utilty on MajorGeeks)

    Thanks -Joe
     
  2. Rick

    Rick TechSpot Staff Posts: 4,573   +65

    Modern hard drives are so fast anymore, it does little good for most users to defragment regularly. But I guess a good defrag after moving a few gigabytes of data or more couldn't hurt. Maybe defrag before or after you install a big game or large application. Defrag if you move your media libraries around...

    But don't defrag every day. It's honestly too much micro management for a negligible 'performance' increase.
     
  3. Blakhart

    Blakhart TS Rookie Posts: 353

    As above. And unless you did the aid0 for reasons of disk space or video editing/other large contigous file use, aid0 is not going to give you much of a performance boost over the drives running in a jbod or aid1 array. Too, if one gets corrupted, the array is dead.
     
  4. Sparky Joe

    Sparky Joe TS Rookie Topic Starter Posts: 18

    So lately I've been looking at the de-frag analysis. This morning I was at 53%fragmented, so I removed a lot of files that did not need to be part of the de-frag and checked the analysis again, now it's at 6% fragmented. It would appear that this raid set is not more subjectable to fragmentation like I heard. Thanks for all the input.

    And thanks Blackhart, but trust me, every time I say the word raid-0 around here I hear the same thing, and then I say video editing is what I do and that all my important stuff is backed up to dvd. I did plenty of research before I set up the array, and did see jbod, but didn't read about it, what is it? Something about a 'bunch of disks'?

    -Joe
     
  5. Rick

    Rick TechSpot Staff Posts: 4,573   +65

    JBOD isn't very useful, in my opinion. I would have chosen RAID 0 myself, if presented with the choice.

    I have RAID 0 (160GB x 2, 32kb stripe size) and I can tell you there's not a lot of difference. Benchmarks tell me my RAID 0 increases sustained transfer performance by about 20%. But I'd be lying if I told you I noticed.

    I've set up a file server with a couple of 500GB drives. So I'm probably getting rid of the RAID 0 because I don't need the space anymore. I might use the disks independently for a software backup or reconfigure to RAID 1 (which also provides a performance boost, just for reads)... Or perhaps implement both.

    O&O Defrag = my favorite. :)

    I'm not sure RAID 0 means impending doom. There is an increased risk of data loss because you have more variables to account for, but I don't feel like its much.

    The idea is now you have to worry about two drives instead of one (doubles the potential of drive failure, which would affect the entire array) and controller/striping issues from firmware bugs, brown-outs etc... But as long as you keep things backup, there's not much to worry about.
     
  6. es84

    es84 TS Rookie Posts: 48

    hi
    i think there is no need to de frag the system if u are running sata hdd

    Raid 0 on home pc is mostly on SATA hard drive , and sata stores data in serail form , i read some where that sata hdd and de frag is not recommended
    u will spoil the hard drive ,
    defrag i s needed on parallel drives thats get slow ,
     
  7. jobeard

    jobeard TS Ambassador Posts: 9,342   +622

    one of the nicest features of a SCSI Raid implementation, is the overhead is
    off loaded to the controller. This also creates a brownie point for completing
    an I/O operation even though the OS froze-up, which is not true for the IDE
    hosted solution.

    For a STRIPEd implementation, fragmentation is irrelevant;
    for a MIRROR, it's important.
     
  8. Nodsu

    Nodsu TS Rookie Posts: 5,837   +6

    Filesystem fragmentation has absolutely nothing to do with the underlying hardware. You get exactly the same fragmentation no matter if you use tape, floppies, IDE hard drives, SCSI hard drives, SATA hard drives, CD-RWs, file-backed virtual filesystems, monster RAID arrays, RAM disks or whatever.

    Filesystem fragmentation has got everything to do with the filesystem type/configuration and how you use it. Keep constantly changing data (p2p downloads) away from your system files. Don't let the filesystems get full. Use bigger cluster sizes if you have big files.
     
  9. jobeard

    jobeard TS Ambassador Posts: 9,342   +622

    in a STRIPEd configuration every sucessive record is on 'the other drive' and
    the seek+latency for the N+1 record is covered over by the transfer of N.
    the more HDs being striped, the less importance of seek+latency becomes,
    and therefore fragmentation is a non-issue.

    in a MIRRORed config, both/all drives operate in parallel and the operation is not
    complete until ALL are complete. thus, bad-block swapping and fragmentation
    become real issues to performance.
     
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