RAID1 + FireWire 800 external disk...

[lasse]

Hi,
I came up with an idea the other day. Basically I'm trying to kill two birds with one stone. I thought that if I create a RAID-1 setup between an internal disk and a really fast external FireWire 800 drive, I should be able to get a RAID setup as well as a basic security improvement, i.e whenever we go away I can shut the machine down and pack the FW disk. Then some tosser thief can come and pilfer my PC while I'm enjoying my holidays and I stll have my data.

Perhaps this is a really bad idea but I thought it might be worth a go so I've played with it today. I can set up the mirrors fine. I have 9 mirrored partitions and after having created them using mkraid using them are fine. I can see in /proc/mdstat that the mirrors reflect the setup in /etc/raidtab.

The problem is that after a reboot the FW partitions (/dev/sda*) are missing from the corresponding /dev/md*. I have IEEEE1394 compiled as a module and I have added 'sbp2' to /etc/modules.autoload.d/kernel-2.6. If I recreate the raid devices all partitions (incl FW) appear as expected.

I have verified that the module loads before the RAID partitions are found (which is immediately after the sbp2-module has been modprobed).

I'm guessing that either I'm missing something basic about RAID or perhaps the FireWire partitions haven't been finally set up when the RAID train gets going.

Is there a way to handle this or am I trying to do something that simply isn't supposed or expected to work?

Thanks for your help.

/Lasse

[GordSki]

I think you probably right about the firewire disk not being ready before the raid array kicks off.
Have you tried with the SBP2 support compiled directly into the kernel, rather than as a module?
This should mean that the drive appears sooner in the boot process.

G.

[Sachankara]

Yep, he has to compile the drivers into the kernel, not as modules.
_________________
Gentoo Hardened Linux 2.6.21 + svorak (Swedish dvorak)

[s0be]

Ok, close to a week old, but I thought I'd try to remember my software raid days to answer a question...

I do believe that the kernel detects the raids during the time in which it's scanning the partition tables to find all it's happy partitions. I know that when I was running one of the myriads of software raid setups (and breaking them) you could watch the kernel reporting the raids before Init fired (which, in turn is before the modules are loaded). This is reaffirmed by the fact that you can make the nodes after the module is loaded and have it work.

Notes about how I was configured:

Raid Support Built into kernel
Appropriate raid levels built into kernel
All controllers/discs drivers built into kernel AND plugged in at boot.
All partitions marked as linux raid autodetect(type fd)

Now, it would be neat if somone could create a raid 0.5 that, when detecting a particular removable storage device, started rebuilding a raid 1 array between it and your current live system. Once sync'd up, it wouldn't be safe to remove it until a safe shutdown happens, but I'd love a backup solution I could just plugin before going to bed each night, knowing it's done when I wake up in the morning.