
DRBD - block device which is designed to build high availability clusters - brk
http://www.drbd.org/
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rcoder
I used DRBD to build a replicated PostgreSQL setup a couple of years ago:
<http://people.reed.edu/~lennon/scaling.html>

It worked pretty well, but the write speed was probably about 1/4 to 1/5 that
of a local database. We've sense moved to log-shipping as a replication model.

We do still use DRBD for some replicated NFS shares, and it's proven to be
pretty trouble-free. (Knock on wood.)

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delano
What is the advantage of "network raid-1" over raid-1? It seems to me that
block replication is best left below the OS.

~~~
wmf
Some people don't want to pay for dual-controller hardware RAID, so DRBD is
the software equivalent.

~~~
rcoder
The description of DRBD as software RAID is a bit misleading, since in most
deployment scenarios, only the "primary" node of the pair can actually write
data to the replicated volume.

It's real use is in building high-availability services -- since the
"mirrored" disks aren't in the same box, you can have an up-to-the-second copy
of the data there. The two systems don't even have to be in the rack next to
each other, which is a tough trick to pull off with normal hardware RAID.

As I said in my other comment, though, it is a lot slower than native disk
writes.

