On 10/17/13 20:57, Nick Holland wrote:
with the exception of the fact there's no code to rebuild a failed
disk, works great. that's a pretty big exception for most people. :)
Hmm. That would present a problem.
Let me make sure I'm absolutely clear here:
A RAID5 array with four disks. I notice via bioctl(8) that one has
failed. I pull the failed disk and replace it with my cold spare. I
cannot use bioctl -R to incorporate the new disk into the array.
Correct? (BTW, I know for a fact it works properly with RAID1.)
So basically, if a drive fails, the RAID5 array is permanently borked
until completely recreated with a new array, meanwhile I'll be trying to
"back up" my data somewhere else.
you should be trying this stuff yourself. Doesn't matter if *I* can
rebuild your array, it matters if YOU can. You don't have to practice
on 3TB disks, you can practice on 10GB disks...though understanding
the time required for 3TB disks would be wise.
As you've often advised in the past, test it yourself. I plan on it,
just to see what happens. BTW, I tried it once with a 3TB RAID1, and I
believe it took two days, but I could be wrong and is
hardware-dependent. Either way, it takes a /long/-ass time.
other than a 3TB disk is closer to 2.75TB than 3TB, yeah the math
works the same with softraid as it does with hw raid. Nick.
Yes, sorry for not making clear I realize that. I didn't want to do the
usable space, GB/GiB, TB/TiB dance. "You know what I mean..", hopefully.
Either way, while I have the opportunity, I'm going to create some RAID5
arrays of varying sizes, pull ("fail") disks, etc., and just see what
happens for myself. Experimenting is fun!
Unfortunately, if RAID5 cannot rebuild anything, it's about as useful as
a leaky screwdriver and RAID1 remains the only viable option on
OpenBSD. Damn.
Thanks Nick, as always you're a gem of a resource.
--
Scott McEachern
https://www.blackstaff.ca
"Beware the Four Horsemen of the Information Apocalypse: terrorists, drug dealers,
kidnappers, and child pornographers. Seems like you can scare any public into allowing
the government to do anything with those four." -- Bruce Schneier
