raid of queue length 0

[enami tsugutomo <tsugutomo.enami%jp.sony.com@localhost>]

Hi, all.

It is possible to create raid of queue(fifo) length 0 (see the raidctl
-G output below), and looks as if it works, but reconstruction stalls
once it is interfered by normal I/O.

Does such configuration make sense?  Otherwise raidctl(8) shouldn't
allow it.

enami.

# raidctl -G raid1      
# raidctl config file for /dev/rraid1d

START array
# numRow numCol numSpare
1 2 0

START disks
/dev/vnd0a
/dev/vnd1a

START layout
# sectPerSU SUsPerParityUnit SUsPerReconUnit RAID_level_1
128 1 1 1

START queue
fifo 0