Re: [Dump-users] Dump 10 times slower on faster system

[Bob B. Jr. <bl...@da...>]

Thanks for the suggestion.. using buffer, our larger file systems
maintain an average throughput of around 31 MB/s.

Just using dump direct to tape, the same file system was averaging only
16 MB/s.

    dump -0uf - $FS_NAME | buffer | dd obs=1M of=/dev/nst0

  DUMP: Date of this level 0 dump: Tue Feb 21 23:12:00 2012
  DUMP: Dumping /dev/sda1 (/home) to standard output
  DUMP: Label: none
  DUMP: Writing 10 Kilobyte records
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 175538832 blocks.
  DUMP: Volume 1 started with block 1 at: Tue Feb 21 23:12:08 2012
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: 4.58% done at 26821 kB/s, finished in 1:44
  DUMP: 10.51% done at 30750 kB/s, finished in 1:25
  DUMP: 15.37% done at 29982 kB/s, finished in 1:22
  DUMP: 21.89% done at 31963 kB/s, finished in 1:11
  DUMP: 30.82% done at 36013 kB/s, finished in 0:56
  DUMP: 35.73% done at 34804 kB/s, finished in 0:54
  DUMP: 41.75% done at 34865 kB/s, finished in 0:48
  DUMP: 46.14% done at 33719 kB/s, finished in 0:46
  DUMP: 50.72% done at 32948 kB/s, finished in 0:43
  DUMP: 56.23% done at 32878 kB/s, finished in 0:38
  DUMP: 62.16% done at 33044 kB/s, finished in 0:33
  DUMP: 67.11% done at 32703 kB/s, finished in 0:29
  DUMP: 71.28% done at 32068 kB/s, finished in 0:26
  DUMP: 76.26% done at 31859 kB/s, finished in 0:21
  DUMP: 80.57% done at 31415 kB/s, finished in 0:18
  DUMP: 84.47% done at 30878 kB/s, finished in 0:14
  DUMP: 89.15% done at 30672 kB/s, finished in 0:10
  DUMP: 94.93% done at 30848 kB/s, finished in 0:04
  DUMP: 99.12% done at 30514 kB/s, finished in 0:00
  DUMP: Volume 1 completed at: Wed Feb 22 00:48:12 2012
  DUMP: Volume 1 175145930 blocks (171040.95MB)
  DUMP: Volume 1 took 1:36:04
  DUMP: Volume 1 transfer rate: 30386 kB/s
  DUMP: 175145930 blocks (171040.95MB)
  DUMP: finished in 5764 seconds, throughput 30386 kBytes/sec
  DUMP: Date of this level 0 dump: Tue Feb 21 23:12:00 2012
  DUMP: Date this dump completed:  Wed Feb 22 00:48:12 2012
  DUMP: Average transfer rate: 30386 kB/s
  DUMP: DUMP IS DONE
350291860+0 records in
171040+1 records out
179349432320 bytes (179 GB) copied, 5760.42 s, 31.1 MB/s



On Tue, 2012-02-14 at 21:15 +0000, dk...@ly... wrote:
> > All interfaces are SAS, I can do dd reads from tape at 150 MB/s from
> both
> > systems.
> >
> > Trying to determine if this is kernel related (st module) or dump
> related
> > or ext3/4 related.
> 
> Have you tried using some buffering between the dump program and the
> tape? 
> Something like 
>  
>       <dump'n'all> | dd ibs=512 obs=1M of=$TAPE
>  
> so dump doesn't need to wait for the tape to confirm that the block
> had been 
> written, dd does that and less often. Tapes should acknowledge
> the block as 
> soon as it's been received in the cache, before really committing it
> to tape, 
> but even that "as soon as" may be stalling the process for some
> reason.
>  
> There is a utility called "buffer" which is supposed to do the
> buffering with 
> more options. Try it and and let us know if it speeds up the dump
> backup in 
> your case. 
> 
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