Re: [MooseFS-Users] Multiple CRC failures

[Gandalf C. <gan...@gm...>]

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?
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,
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)