It wasn't planned this way, it just happened over time, but I ended up
with a couple of machines with a few 3TB RAID1 volumes. As a result,
around 18TB total (all HDDs are 3TB) is actually 9TB once RAID1'd.
Circumstances change, and I might be able to redeploy those HDDs as a
RAID5 array. This, at least in theory, would allow the 18TB total to be
realized as 15TB as RAID5, gaining me 6TB. For now, I'm able to "back
up" my RAID1 arrays to non-RAID HDDs. While this makes me nervous, I
want to at least try creating a RAID5 setup to experiment on, with an
eye to fully replacing RAID1 with RAID5. (6TB of "lost" capacity is
nothing to sneeze at!)
I realize the bioctl(8) man page says "Use of the CRYPTO & RAID 4/5
disciplines are currently considered experimental."
However, I've been using RAID1 and CRYTPO in bootable and non-bootable
configurations, including full disk encryption, quite happily for a
while now. I've tested by removing drives, booting, rebuilding, etc.,
and I've never had a problem. So while the page may say "experimental",
I've found CRYPTO to be rock-solid thus far.
I've never tried softraid's RAID5, so I have no idea if it truly is
"experimental", or solid like CRYPTO, or somewhere in between.
So I ask my fellow list'ers for their experiences with OpenBSD's RAID5
implementation. (Yes, I'm running -current.) Does it "work" for you?
Have you had any good experiences? Any bad experiences? Have you had to
actually rebuild a RAID5 array? Can you add another drive to the array
at a later time, or does the array need to be destroyed and rebuilt from
scratch? Any questions I'm forgetting? I need to know about these
things, from real-world use, before using RAID5 in the long-term.
Also, in theory, with RAID5 you only "lose" one drive for the parity,
hence my "18TB non-RAID => 15TB RAID5" math. Is this correct in
practise with softraid?
All stories are welcome, including private emails.
Thanks,
--
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
