gmirror rebuilds on every reboot

[Andrea Venturoli]

As per subject: I have a 5.3 box with two SATA drives and I using 
gmirror to achieve RAID 1.
The problem is it started rebuilding the array *on every boot*.

 From the logs:

Mar 12 16:39:16 robert kernel: ad4: 78167MB <Maxtor 6Y080M0/YAR511W0> 
[158816/16/63] at ata2-master SATA150
Mar 12 16:39:16 robert kernel: ad6: 78167MB <Maxtor 6Y080M0/YAR511W0> 
[158816/16/63] at ata3-master SATA150
Mar 12 16:39:16 robert kernel: GEOM_MIRROR: Device gm0 created 
(id=2197339280).
Mar 12 16:39:16 robert kernel: GEOM_MIRROR: Device gm0: provider ad4 
detected.
Mar 12 16:39:16 robert kernel: GEOM_MIRROR: Device gm0: provider ad6 
detected.
Mar 12 16:39:16 robert kernel: GEOM_MIRROR: Device gm0: provider ad6 
activated.
Mar 12 16:39:16 robert kernel: GEOM_MIRROR: Device gm0: provider 
mirror/gm0 launched.
Mar 12 16:39:16 robert kernel: GEOM_MIRROR: Device gm0: rebuilding 
provider ad4.




fdisk /dev/ad4 (same for /dev/ad6 or /dev/mirror/gm0) gives:

******* Working on device /dev/ad4 *******
parameters extracted from in-core disklabel are:
cylinders=158816 heads=16 sectors/track=63 (1008 blks/cyl)

Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=158816 heads=16 sectors/track=63 (1008 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
     start 63, size 160071597 (78159 Meg), flag 80 (active)
         beg: cyl 0/ head 1/ sector 1;
         end: cyl 747/ head 254/ sector 63
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>




bsdlabel /dev/mirror/gm0s1:

# /dev/mirror/gm0s1:
8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
   a:  1048576       16    4.2BSD     2048 16384     8
   b:  4194304  1048592      swap
   c: 160071597        0    unused        0     0         # "raw" part, 
don't edi
t
   d: 41943040  5242896    4.2BSD     2048 16384 28552

(Yes, I left some space unused.)




Finally /etc/fstab:

# Device             Mountpoint   FStype  Options      Dump  Pass#
/dev/mirror/gm0s1b   none         swap    sw           0     0
/dev/mirror/gm0s1a   /            ufs     rw           1     1
/dev/mirror/gm0s1d   /usr         ufs     rw           2     2
/dev/acd0            /cdrom       cd9660  ro,noauto    0     0



And I have swapoff="YES" in /etc/rc.conf.



I cannot think of any reason this might happen, but I'd appreciate any 
hint to avoid that.


  bye & Thanks
	av.