Thanks. I'd consider raid6, but since I'll be backing up to a second
btrfs raid5 array, I think I have sufficient redundancy, since
equivalent to raid 5+1 on paper. I'm doing that rather than something
like raid10 in a single box because I want the redundancy of a second
physical server so I can failover in the event of a system-level
component failure.
(And of course, "failover" means "continue being able to watch TV shows
and stuff")
A question about what you said -- when you say people have hit bugs in
the raid56 code, which flavor do these bugs tend to be? Are they
"minding my own business and suddenly it falls over" bugs or "I tried to
do something weird with btrfs and it screwed up" bugs?
Thanks,
Tyler
On 8/18/2015 7:42 AM, Austin S Hemmelgarn wrote:
On 2015-08-17 15:18, Tyler Bletsch wrote:
Thanks. I will be trying raid5 in production, but "production" in this
case just means my home file server, with btrfs snapshot+sync for all
data and appropriate offsite non-btrfs backups for critical data. If it
hoses up, I'll post a bug report.
So far, that's been my use case for btrfs raid6, and (barring one bug
I found involving an interaction between btrfs and thinly provisioned
storage that shouldn't be an issue for you if you're not using LVM
thin pools) I have yet to hit any bugs, although based on the lists,
I've probably been _very_ lucky in that respect. If you're willing to
take a marginal performance hit (about 1-3% in my experience, which is
notably less than the performance difference between MD-RAID5 and
MD-RAID6), and have at least four disks, I'd suggest using btrfs's
raid6 profile instead of raid5, they use exactly the same code, it's
just that raid6 has one more calculation involved and provides better
protection against data corruption due to the double parity.
Going to try to avoid LVM, since half the appeal of btrfs for me is
getting away from the multiple duct-taped layers of indirection that I
you get currently with ext4/MD/LVM setups.
Understandable, my main reasons for having LVM are storing virtual
machine disk images and the fact that MD/DM raid is still ridiculously
fast compared to btrfs raid (many of my btrfs raid volumes are
themselves on top of LVM managed software raid0 or raid1 volumes).
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