zvol device weirdness after memory corruption?

[Jeff Rizzo <riz%tastylime.net@localhost>]

I just removed some bad RAM from a system where I was definitely seeing 
memory corruption (md5 on large files would return nearly-random results 
- yes, I know I should use ECC but that's not an option on this 
motherboard).  The bad RAM is gone, and I don't seem to be seeing the 
same issues any more.

The odd thing is what the zpool on this system has done - mind you, a 
scrub of the 120G on there never turned up any issues - is that 
formerly-working zvols are now returning errors when attempting to use 
them as devices:


# ccdconfig ccd0 1 /dev/zvol/dsk/tank/volumes/tempzvol
ccdconfig: ioctl (CCDIOCSET): /dev/rccd0d: Invalid argument


...and this is for both existing zvols and newly-created ones. Since I 
have backups and not a lot of used space on the zpool yet, I will 
probably wind up re-creating it, but before I do that: does anyone know 
what specific settings/changes/corruption might cause this?  I don't see 
anything in dmesg or `zpool status` - and zvols were definitely working 
like this before.  (and the backups on a separate system of some of the 
*same* zvols are working now)