Uneven load on drives in ZFS RAIDZ1

[Michael Reifenberger]

Hi,
a quick test using `dd if=/dev/zero of=/test ...` shows:

dT: 10.004s  w: 10.000s  filter: ^a?da?.$
  L(q)  ops/s    r/s   kBps   ms/r    w/s   kBps   ms/w   %busy Name
     0    378      0      0   12.5    376  36414   11.9   60.6| ada0
     0    380      0      0   12.2    378  36501   11.8   60.0| ada1
     0    382      0      0    7.7    380  36847   11.6   59.2| ada2
     0    375      0      0    7.4    374  36164    9.6   51.3| ada3
     0    377      0      1   10.2    375  36325   10.1   53.3| ada4
    10    391      0      0   39.3    389  38064   15.7   80.2| ada5

Seems to be sufficiently equally distributed for a life system...

zpool status shows:
...
         NAME        STATE     READ WRITE CKSUM
         boot        ONLINE       0     0     0
           raidz1-0  ONLINE       0     0     0
             ada0p3  ONLINE       0     0     0
             ada1p3  ONLINE       0     0     0
             ada2p3  ONLINE       0     0     0
             ada3p3  ONLINE       0     0     0
             ada4p3  ONLINE       0     0     0
             ada5p3  ONLINE       0     0     0
...

The only cases I've seen (and expected to see) unequal load distributions on ZFS 
was after extending a nearly full four disk mirror pool by additional two disks.


Bye/2
---
Michael Reifenberger
Michael at Reifenberger.com
http://www.Reifenberger.com