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Thread: dump capacity?

  1. #1
    Join Date
    Oct 2006
    Posts
    27

    Default dump throughput?

    Hi folks,

    after having installed a SW-RAID1-stack consisting of 2 SATA-HDs, I receive a dumping-throughput of roughly 0.85MB/s. There are 2 raid-devices on that new stack which act as dumping disks. On the same harddisks are non-RAID-partitions which are dumped onto the RAID-partitions.

    0.85MB/s seem to be quite little to me, for on a stoneage-hardware I measure 225MB/s dumping throughput.

    Any ideas?

    Thanks & cheers & greets from Vienna

    Mat

    inserted: It's this very moment that an idea occured to myself: it seems, as if only those non-RAID-partitions are causing trouble when being read, and this might be a problem of authorization! I'll investigate this and post here...

    inserted: I've fiddled around with the partitions now having *reversed* the direction of the dump: the dump disks are now plain partitions whereas the data comes from RAID-stacks. 1.5MB/s is the throughput :-( ANY ideas?

    inserted: update! by now dump rate went up to approx. 40MB/s (which is still ridiculous)
    Last edited by phaidros; October 13th, 2006 at 05:26 AM.

  2. #2
    Join Date
    Oct 2005
    Posts
    1,559

    Default

    Hi Mat,

    What do you mean by dump rate? Rate of transfer from the client to holding disk.

    Is your holding disk and filesystem you are backing up part of the same RAID?

    Are you using holding disks? or are you backing up to vtape (backup media) directly?

    To understand your problem, we need information on where filesystem being backed up,
    holding disk(s) (if any) and vtape (backup media) reside. Amreport output will be useful.

    Are you using compression or encryption?

    Thanks,
    Paddy

  3. #3
    Join Date
    Oct 2006
    Posts
    27

    Default

    Quote Originally Posted by paddy
    Hi Mat,

    What do you mean by dump rate? Rate of transfer from the client to holding disk.
    Exactly. The client *is* the tapeserver itself, in this case.

    Quote Originally Posted by paddy
    Is your holding disk and filesystem you are backing up part of the same RAID?
    No, they're not: the holding disk is on a non-raid-partition on one of the two HDs, which make up the RAID-stack.

    Quote Originally Posted by paddy
    Are you using holding disks? or are you backing up to vtape (backup media) directly?
    Yes, I am. See my previous post and above.

    Quote Originally Posted by paddy
    To understand your problem, we need information on where filesystem being backed up,
    holding disk(s) (if any) and vtape (backup media) reside. Amreport output will be useful.

    Are you using compression or encryption?
    In the meanwhile, this has occurred to myself: I am in fact using compression, and the low rate is probably only due to compression! So it seems as if everything worked just fine. That is: everything except my head! I'll verify this during the next week and let you know.

    Thanks so far,
    Mat

  4. #4
    Join Date
    Oct 2006
    Posts
    27

    Default Solved: dump performance problem

    All right, ladies & gentlemen:

    this was not my smartest posting - I couldn't wait and tried immediately and the result was convincing: it was simply compression of data which took the throughput down into the cellar. I just disabled compression and measured 23MB/s, which looks more like what I wanted to see in the first place.

    Thank you all the same, folks!

    Bests
    Mat

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