Re: [MooseFS-Users] Resiliency to temporary loss of chunk server

[Aleksander W. <ale...@mo...>]

Hello.

MooseFS is very resilient in many aspects not only in chunkserver actions.

I would like to say about two main chunkserver conditions:

1. Chunkserver Loose:
Let's say that our MooseFS cluster consist of 4 components(1x mfsmaster,
3x mfschunkserver) and minimum GAOAL is set to 2.
In this case it means that one chunkserver can be powered down,
unplugged from network or die without any data loose.

After loosing a chunkserver replication process starts. It means, that
all chunks without extra copy are replicated to another chunkservers to
achieve GOAL2.

GOAL - mean how many copies of chunks will be available on different
chunkservers.
MooseFS never keeps more than one copy on the same chunkserver!

2. Maintenance mode
When we turn on maintenance mode and stop process for specific
chunkserver, no extra copy for under GOAL chunks will be made. Also no
write operations will be executed.
More details about maintenance mode can be found in paragraph 4.3
"Maintenance mode" in our MooseFS 2.0 manual:
http://moosefs.com/Content/Downloads/MooseFS-2-0-60-User-Manual.pdf

Maintenance mode option can be on and off from CGI web page or from
command line.

Best regards
Aleksander Wieliczko
Technical Support Engineer
MooseFS.com <moosefs.com>

On 08.09.2015 22:04, Warren Myers wrote:
> How resilient is MooseFS to temporarily losing a chunk server - say
> doing hardware maintenance, migration to a new datacenter, VM
> migration, etc?
>
> *Warren Myers*
> http://antipaucity.com
> https://www.digitalocean.com/?refcode=d197a961987a
>
>
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