[Tfug] Really slow mdadm resyncing

[Matt Jacob]

Hey guys:

I just set up a box with Debian etch, and I'm using mdadm with 2 IDE
drives in RAID1. I rsync'd about 50G of data to the box today, and
that finished at around 9:00 or 10:00 this morning. More than twelve
hours later, the RAID is still "active, resyncing", and I can't figure
out why. I don't even know what that means (I thought the status was
supposed to be "dirty" while recovering).

Here's the output from mdadm:

ned:~# mdadm -D /dev/md2
/dev/md2:
        Version : 00.90.03
  Creation Time : Sat Jun 16 11:45:51 2007
     Raid Level : raid1
     Array Size : 159139776 (151.77 GiB 162.96 GB)
    Device Size : 159139776 (151.77 GiB 162.96 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 2
    Persistence : Superblock is persistent

    Update Time : Sat Jun 16 18:36:02 2007
          State : active, resyncing
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

 Rebuild Status : 64% complete

           UUID : 7f38bf9f:27f5bf50:05d2898a:691e38c1
         Events : 0.9

    Number   Major   Minor   RaidDevice State
       0      33        3        0      active sync   /dev/hde3
       1      33       67        1      active sync   /dev/hdf3


And then there's this, which shows a pathetic 1M/s transfer rate:

ned:~# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 hde3[0] hdf3[1]
      159139776 blocks [2/2] [UU]
      [============>........]  resync = 64.3% (102406080/159139776)
finish=830.1min speed=1137K/sec

md1 : active raid1 hde2[0] hdf2[1]
      746944 blocks [2/2] [UU]

md0 : active raid1 hde1[0] hdf1[1]
      192640 blocks [2/2] [UU]

unused devices: <none>


The strange thing is that my speed_limit_min is set to 50000, which
should be 50M/s:

ned:~# cat /proc/sys/dev/raid/speed_limit_min
50000

Any ideas? Am I missing something? If I can't get better performance
out of this thing, I'm gonna go back to my poor man's RAID which
consisted of a nightly rsync job between the two drives.

Matt

P.S. Here are my system specs: Athlon 1200 MHz, 768 M RAM, (2) IDE ATA100 drives