amd64/147560: Booting 8.1-PRERELEASE raidz system take ages

[Krzysztof Dajka]

>Number:         147560
>Category:       amd64
>Synopsis:       Booting 8.1-PRERELEASE raidz system take ages
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-amd64
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Jun 06 12:40:04 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     Krzysztof Dajka
>Release:        8.1-PRERELEASE
>Organization:
>Environment:
FreeBSD altstation 8.1-PRERELEASE FreeBSD 8.1-PRERELEASE #0: Thu Jun  3 09:58:00 CEST 2010     toor at altstation:/usr/obj/usr/src/sys/GENERIC  amd64
>Description:
I'm booting from usb memory stick with updated bootcode.
Bootstraping process:

 BTX loader 1.00 BTX version is 1.01
 Console: internal video/keyboard
 BIOS drive C: is disk0
 BIOS drive D: is disk1
 BIOS drive E: is disk2
 BIOS drive F: is disk3
 |
It freezes in this state for over 40 seconds and after that boots normally. I have even tried booting over pxe, I created 1M file  

I have following raidz configuration:

$  gpart show                       
=>       34  976773101  ada0  GPT  (466G)
         34  976773101     1  freebsd-zfs  (466G)

=>       34  976773101  ada1  GPT  (466G)
         34  976773101     1  freebsd-zfs  (466G)

=>       34  976773101  ada2  GPT  (466G)
         34  976773101     1  freebsd-zfs  (466G)

=>   34  60733  da0  GPT  (30M)
     34    128    1  freebsd-boot  (64K)
    162  60605       - free -  (30M)

$  zpool status
  pool: zroot
 state: ONLINE
status: The pool is formatted using an older on-disk format.  The pool can
        still be used, but some features are unavailable.
action: Upgrade the pool using 'zpool upgrade'.  Once this is done, the
        pool will no longer be accessible on older software versions.
 scrub: none requested
config:

        NAME           STATE     READ WRITE CKSUM
        zroot          ONLINE       0     0     0
          raidz1       ONLINE       0     0     0
            gpt/disk0  ONLINE       0     0     0
            gpt/disk1  ONLINE       0     0     0
            gpt/disk2  ONLINE       0     0     0


>How-To-Repeat:
Update to 8.1-PRERELEASE, update bootcode 
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: