Ken Gunderson wrote: > Greets: > > I've been exploring root on raidframe w/a pair of mirrored disks. Once > I bring something like this up I then go ahead and do my best to break > it, test out recovery scenarios, etc.
smart. VERY smart. :) > Which brings me to the question > at hand. > > Following a hard failure the system must perfomr a parity check on > the raid volume(s) prior to fsck'ing and completing booting. Depending > on disk size, speed, and number of volumes, this can easly require a > few hours of wait time before being able to bring the system back > online. > > Now my question is whether there is some way to shorten > this delay that I'm missing? yes. RAIDframe as absolutely little as you NEED to. Soft-mirroring (or hardware-mirroring, for that matter) more than you absolutely need to is foolish. Let's look at a simple mail server for an example (since you didn't describe your app): / /usr /var /home /var/mail /tmp Where does stuff change rapidly and critical to not lose even a minute's worth of change if possible? /var/mail, probably. MAYBE /home. So, RAIDframe those. / ? Use the "altroot" process for that. /usr ? dump/restore it to a second disk nightly or weekly. /tmp ? well, as I'm basically assuming your system is going down if a drive fails, I'm going to argue that /tmp does not need to be mirrored. You probably don't need to be mirroring your /usr/src, /usr/ports or /usr/obj directories, even if you really DID want to mirror /, /usr, /tmp, and friends. Now, after an "event", only /var/mail (and maybe /home) have to be rebuilt. One nice thing about RAIDframe (or ccd(4)) is that you can mirror only a little slice of a big drive if you so desire. Even if you want to keep the entire system mirrored, you could probably get away with a 2G or 600M system for a lot of applications, rather than 80G or whatever the smallest disk you can get now is. With HW mirroring, you end up doing the entire 80G (or 250G when the purchasing dept. says, "hey, it was only $20 more, so we got the bigger one!") Yes, it isn't The Solution for all situations, but it helps in a lot of places. Nick.
