Re: [Moosefs-users] git outdated

[Michał B. <mic...@ge...>]

> El Jue 03 Junio 2010, Laurent Wandrebeck escribió:
> > On Thu, 3 Jun 2010 09:02:29 +0200
> > - Do you know of any « big user » relying on mfs ? I've been able to find
> > several for glusterfs for example, nothing for moosefs. Such entries would
> > be nice on the website, and reassuring for potential users.
> 
> Well, I was pretty sure I saw a "Who's using" section on the website but I
> can't find it. Indeed it would be nice to have one.
[MB] No, it has not been yet created. We plan to implement it.

[MB] At our company (http://www.gemius.com) we have four deployments, the biggest has almost 30 million files distributed over 70 chunk servers having a total space of 570TiB. Chunkserver machines at the same time are used to make other calculations. 

[MB] Another big Polish company which uses MooseFS for data storage is Redefine (http://www.redefine.pl/).



> > I've read that you have something like half a PB. We're up to 70TB, 
> > going to 200 in the next months. Are there any known limits, bottlenecks, 
> > loads that push systems/network on their knees ? We are processing satellite 
> > images, so I/O is quite heavy, and I'm worrying a bit about the behaviour 
> > during real processing load.
[MB] You can have a look at this FAQ entry: 
http://www.moosefs.org/moosefs-faq.html#mtu  

[MB] At our environment we use SATA disks and while making lots of additional calculations on chunkservers we even do not fully use the available bandwidth of the network. If you will use SAS disks it can happen that there would appear some problems we have not yet encountered. 



[ ... snip ... ]
> > master failover is a bit tricky, which is really annoying for HA.
> 
> That's probably a point for Gluster as it doesn't have a metadata server, but
> actually there is a master (sort of) which is the one the clients connect to.
> 
> If it goes away, there's a delay till another node becomes master, at least in
> theory as I didn't test that part.
[MB] You can also refer to this mini how-to:
http://www.moosefs.org/mini-howtos.html#redundant-master

and see how it is possible to create a fail proof solution using CARP.



[ ... snip ... ]
> > - At last, just to be sure I understood correctly, files are automatically
> > striped through available chunkservers, so for all files with goal at 1, if
> > a single chunkserver falls, files are unavailable, unless they are smaller
> > than 64MB and not on the out of order chunkserver, correct ?
> 
> I believe you're correct, and that's why you should always have at least a
> goal of 2. I mean, if you consider your data important ;)
[MB] Files smaller than 64MB are kept in one chunk and if you set goal=1 and a chunkserver storing this chunk fails, the file is not available.

Bigger files are divided into fragments of 64MB and each of them can be stored on different chunkservers. So there is a quite substantial probability that a big file with goal=1 will be unavailable (or at least its part(s)) if one of the chunks has been stored on the failed chunkserver. 

The general rule is to use goal=2 for normal files and goal=3 for files that are especially important to you.

 

Kind regards
Michał Borychowski 
MooseFS Support Manager
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Gemius S.A.
ul. Wołoska 7, 02-672 Warszawa
Budynek MARS, klatka D
Tel.: +4822 874-41-00
Fax : +4822 874-41-01



> 
> Best regards,
> --
> Ricardo J. Barberis
> Senior SysAdmin - I+D
> Dattatec.com :: Soluciones de Web Hosting
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