RAID 0+1

[Nejc Škoberne]

Hello,

I have FreeBSD 7.0 and 4 250GB SATA disks and I would like to make one big 500GB
0+1 RAID array. My hardware is HP ProLiant ML110G5.

First I tried creating ATA RAID arrays with BIOS tools, but FreeBSD wouldn't 
recognize the arrays.

Than I decided to create the RAID-0 arrays with atacontrol. I succeeded, ending 
up with ar0 and ar1 each 500GB big. My plan was to install the FreeBSD as usual 
on ar0 and then add both into a gmirror array. However, I BootMgr seem not to be 
able to boot from RAID-0 array created with atacontrol? Is this correct? I guess 
this is because BootMgr knows nothing about striping and cannot read the kernel.

Finally I tried to create two slices on each drive. The plan was to join the 
first slice of all 4 drives into a gmirror array and mount it as / partition (I 
guess BootMgr would boot normally from such an array). Then I would merge the 
second slice of all 4 drives into a 0+1 array (first gstriping and then 
gmirroring them). I somehow succeeded this, but I also get a WARNING when 
booting the system:

ad0: 238475MB <WDC WD2500YS-70SHB1 20.06C06> at ata0-master SATA150
ad1: 238475MB <Seagate ST3250620NS 3BJP> at ata0-slave SATA150
ad2: 238475MB <GB0250C8045 HPG1> at ata1-master SATA150
GEOM_STRIPE: Device gs0 created (id=2160028923).
GEOM_STRIPE: Disk ad0s2 attached to gs0.
ad3: 238475MB <GB0250C8045 HPG1> at ata1-slave SATA150
GEOM_STRIPE: Disk ad1s2 attached to gs0.
GEOM_STRIPE: Device gs0 activated.
GEOM_STRIPE: Device gs1 created (id=3269017453).
GEOM_STRIPE: Disk ad2s2 attached to gs1.
GEOM_MIRROR: Device mirror/gm0 launched (4/4).
GEOM_STRIPE: Disk ad3s2 attached to gs1.
GEOM_STRIPE: Device gs1 activated.
WARNING: Expected rawoffset 0, found 63
GEOM_MIRROR: Device mirror/gm1 launched (1/2).
GEOM_MIRROR: Device gm1: rebuilding provider stripe/gs1.

Is this critical? It looks like the system is fine, though.

Is there any "more proper" way to build such a system with RAID 0+1?

Thanks,
Nejc