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From Adam Kocoloski <kocol...@apache.org>
Subject Re: Backup for 2.x
Date Thu, 08 Dec 2016 19:24:46 GMT
Kinda.

Yes, every file in the shards folder is using the same basic copy-on-write file format as
v1. The challenge is that a single logical database has multiple physical shards potentially
spread across multiple hosts. Capturing the state of each of those shard files _at the same
point in time_ can be a challenge, but is technically the sort of thing that’s required
to get to the same consistency semantics as the file-based backup option in v1. If you copy
the files at different points in time the restored database won't correspond to a snapshot
of the database at any particular point in time.

Using a snapshotting filesystem (LVM, ZFS, etc.) and copying the _snapshot_ of the shards
directory to a different host is something worth considering here. Cheers,

Adam

> On Dec 8, 2016, at 5:23 AM, Reddy B. <reddy.b@live.fr> wrote:
> 
> Hi all,
> 
> The ability to backup as easily as by copying a file was really useful in version 1 as
it allowed us to take advantage of a large array of general purpose backup tools.
> 
> In 2.x, is it safe to just copy the "shards" folder assuming that we intend to "restore"
it on a cluster having the same configuration ?


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