Re: [MooseFS-Users] Questions about Maintenance Mode

[Piotr R. K. <pio...@mo...>]

Hi Steve,

It will be possible to answer your question middle next week the earliest.
I am sorry for the delay in advance

Best,
Piotr

Piotr Robert Konopelko | m: +48 601 476 440 | e: pio...@mo... <mailto:pio...@mo...>
Business & Technical Support Manager
MooseFS Client Support Team

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> On 20 Feb 2019, at 6:42 PM, Wilson, Steven M <st...@pu...> wrote:
> 
> Hi,
> 
> Most of my MooseFS storage systems use two chunk servers and store two copies of each file, one on each chunk server.  I have one very active storage system that has four chunk servers but still only uses a goal of 2.  I need to do some maintenance on one of these chunk servers and was thinking of putting it into maintenance mode so that there wouldn't be any unnecessary replication during the hour or two that this chunk server is out of service.  But I noticed this in the MooseFS 3.0 manual:
> ​
> "Note: If number of Chunkservers in maintenance mode is equal or greater than 20% of all Chunkserver, MooseFS treats all Chunkservers like maintenance mode wouldn’t be enabled at all."
> ​
> If I understand this correctly, I would need at least six active chunk servers before I could take one offline for maintenance.  Is that correct?  If so, what is the reasoning behind this limitation?
> 
> Not only is limiting needless replication important to me but even more important is the blocking of I/O operations to that chunk server while it is being shut down.  Even when I have only two chunk servers, I would like to be able to enable maintenance mode for this particular benefit as described in the manual:
> ​
> "When you turn maintenance mode on for specific Chunkserver a few seconds before stop, MooseFS will finish write operations and won’t start a new ones on this Chunkserver.​"
> 
> ​​As always, thanks for you help and for a terrific distributed filesystem!
> 
> Steve