Re: [MooseFS-Users] Multiple CRC failures

[Jakub Kruszona-Z. <jak...@ge...>]

> On 14 Jun, 2018, at 13:33, Gandalf Corvotempesta <gan...@gm...> wrote:
> 
> Il giorno gio 14 giu 2018 alle ore 13:19 Jakub Kruszona-Zawadzki
> <jak...@ge...> ha scritto:
>> I see that you have goal equal to number of servers. This is rare situation - MFS is usually used in big installation.
>> 
>> For such case I usually need special conditions in the code.
>> 
>> In general such problems are resolved in a way that first I create another copy and only then delete "broken" one. When goal is equal to number of servers than there is no place for creating such valid copy, so first I need to delete "broken" copy and then create valid one on the same server. Maybe this is why system didn't fix it. I'll check it.
> 
> Can't you directly overwrite the broken chunk insted of deleting it?

In general not very good idea. Usually CRC errors means that there is something wrong with this machine.

> Yes, I'm using goal equal to the number of servers, i'll plan to add
> another server (so that i'll have goal=3, 4 masters, 4 chunkservers)
> but keep in mind that allowing goal equal to the number or servers is
> an advantage,

Yes. I only said that it needs to be treated in special way.

> as this will lower the MooseFS TCO. In example, with gluster you can't
> add a single server, you have to add a number of server multiple of
> the redundancy level, in other words, if you start with 3 servers and
> redundancy set to 3, you have to add 3 servers more at once. This has
> a very high operating cost on small installation.
> 
> With Moose there is no need to respect the goal level when adding
> server, thus running with goal=2 and 2 servers or goal=3 and 3 servers
> and adding a single one when needed is an huge advantage
> (that explains why on GH i've asked if HDD removal could move chunks
> to another disk on the same server... you don't need a "spare" server
> for these movements lowering TCO aven more)

-- 
Regards,
Jakub Kruszona-Zawadzki
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