Re: [MooseFS-Users] Minimum setup, local servers, remove VM as a master

[Grouchy S. <sys...@gr...>]

On 06/16/2018 05:32 AM, Nicolas Embriz wrote:
> Hi, I am testing Moosefs on FreeBSD 11 so far using only 2 instances 
> one behaving like master and chunkserver and other only as a 
> chunkserver, so far all pretty good but while testing I notice that if 
> the master goes down all the chunks become unresponsive, In my try to 
> make a more redundant setup I am thinking of using a tiny VM (1GB ram 
> 20GB disk) only to keep the master up and allow the 2 chunks to be 
> operable, but I have some doubts.
>
> If I understand properly the metadata is stored in the master and the 
> chunckservers just store the raw data, therefore the master doesn’t 
> need to be huge in storage as the chunservers , also when writing to 
> data on one chunk server, only the metadata is sent to the master and 
> the raw data is synced only between the chunks, and if I am 
> understanding correctly the more intense use of network/bandwidth is 
> between chunks and not the master, is this correct?  ( thinking on 
> this to have a basic setup in where I could have 2 in home servers in 
> the same network, but only the master in a remote tiny VM "always 
> online" )
>
> Now regarding the master, if it is down, I can’t access /read the 
> files in the chunkservers, is there a way to configure the 
> chunkservers to work in an online mode or being available to continue 
> using what they have to until the master comes back and then just re-sync.
>
> regards.
>
>

The Master server is a single point of failure in MooseFS 3 community 
edition. I believe that is changing in the upcoming MooseFS 4.

The master server should be on the same network as the chunk servers, 
and the clients. Running it remotely  is unlikely to work well.

Since you're on FreeBSD, be aware of 
https://github.com/moosefs/moosefs/issues/89. The fuse implementation on 
FreeBSD 11 can cause several issues including corruption.