[Box Backup] Thoughts on reliability (Was: "Box Backup - corrupted store")

Gary boxbackup@fluffy.co.uk
Thu, 9 Jun 2005 14:26:15 -0700 (PDT)


Hi,

A couple of thoughts on BoxBackup reliability, after reading the
"corrupted store" thread.

> Server is run with userland RAID disabled (...)
> Compress TransformFailed

Does the "atomic" file commits used by BoxBackup apply when RAID is
disabled? I am running a similar setup. I am wondering how a
server-side corruption could have happened, even with no-UPS complete
server power loss. My understanding is that Berkeley-Db should have
rolled back automatically to the last known correct version of each
file (along with client chcecksum blocks)?

Do such circumstances imply that only the latest version is impossible
to restore (lost), or ALL previous versions of a corrupted file?

> usr/local/bin/bbackupquery "compare -aq" (...)
> doesn't write any errors

I think we ran into this before, in a theoretical discussion. It would
imply that server/client block list checking does not actually
cross-check actual data on server hard drive. Given "complete" compares
are overwhelmingly time-consuming (100% download of each file), is
there any way that we could work out to strengthen the quick check?

Just wondering if, and what, I could get my coding into, to make the
system more reliable and sleep better.

Greets to all!

Gary


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