[Gluster-users] Questions about healing

Gandalf Corvotempesta
Fri, 20 May 2016 19:20:07 -0000

Il 20 mag 2016 20:14, "Alastair Neil" <ajneil.tech at gmail.com>
ha scritto:
>
> I think you are confused about what sharding does.   In a sharded replica
3 volume all the shards exist on all the replicas so there is no
distribution.  Might you be getting confused with erasure coding?  The
upshot of sharding is that if you have a failure, instead of healing
multiple gigabyte vm files for example, you only heal the shards that have
changed. This generally shortens the heal time dramatically.

I know what sharding is.
it split each file in multiple, smaller,  chunks

But if all is gonna bad, how can i reconstruct a file from each shard
without gluster? It would be a pain.
Let's assume tens of terabytes of shards to be manually reconstructed ...

Anyway how is possible to keep VM up and running when healing is happening
on a shard? That part of disk image is not accessible and thus the VM could
have some issue on a filesystem.
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