Re: [MooseFS-Users] New user questions

[Wilson, S. M <st...@pu...>]

Bill,

You shouldn't run a metalogger on the same server as the master.  I normally have two to four chunkservers, one of which will also double as the master and another will run the metalogger service.  So, in answer to question #2, I would recommend not running the metalogger on your low-powered systems and only on one or two of the i7's.

My normal procedure for changing to a new master is this (NM is new master, OM is old master):
    a.  stop the master on OM
    b.  stop the metalogger on NM
    c.  copy /var/lib/mfs/metadata* from OM to NM
    d.  drop hostname alias from OM
    e.  add hostname alias to NM
    f.  start up master on NM
    g.  start up metalogger on OM

There are other details, of course, but that covers the main points.

Steve


________________________________
From: William Kenworthy <wil...@gm...>
Sent: Friday, September 27, 2019 5:36 AM
To: moo...@li... <moo...@li...>
Subject: [MooseFS-Users] New user questions


Hi,
        I have set up a small CE moosefs system and would like to clarify some
parts of the documentation:

1. on the master, *should* you run a metalogger - sounds like its
unnecessary?  Does the answer to this change if the master has a
chunkserver attached as well?  If I have enough hardware to run separate
master, metalogger and chunkservers - is this the most desirable setup?

2. Is it good practise to have a metalogger on every chunkserver, or
just one or two? - I assume there could be network problems with too
many, but how many metaloggers to chunkservers is adequate? I am running
some storage on low powered odroid-HC2's and others on i7 hardware so
would like to understand if running on the odroids is not really
necessary even though its possible.

3. Changing to a new master (e.g., hardware maintenance etc, so a
planned event): is it sufficient to:
        a. bring down the current master
        b. change DNS to point to the new master and refresh
        c. on another system with a normally running metalogger, bring
up the new master with -a
        d. on the original master system spin up a new metalogger

* what other intervention would be necessary?

* assume its all been reconfigured

The documentation is good, but unclear on the above as its a generic
document that covers small and large systems in Pro and CE varieties.

BillK