Re: [Moosefs-users] mfs-master[4166]: CS(10.10.10.10) packet too long (226064141/50000000)

[Michał B. <mic...@ge...>]

 

 

Yes I read that page (actually I read every pages of  <http://moosefs.org> moosefs.org to really understand how it works !). 

[MB] Perfect :)

 

It's just a mistake I made to compile it on a 32 bits platform.
But maybe you could tell the dev team that in case of memory allocation failure, mfsmaster crashes without a message... well, if we consider that "segmentation fault" is not a real error message :-)

[MB] It’s on our todo list (but to be honest, with low priority – one cannot expect a 32bit machine to work with more than 4GB RAM :))



 

Maybe later, we'd like to use it for webhosting. But since LOCK is not supported, it's not yet possible.

[MB] What for do you need LOCK for webhosting?


Dynamic websites, writing information to files. Several web servers using the same MooseFS could try to write to the same file in the same time.

 

[MB] It should not be a problem for you. 

 

There is a mechanism of chunk locking for write, but the writing process would be slow. There is no mechanism of informing the client waiting to write that the lock had been released (probably we’ll implement it one time). So now client which couldn’t start writing process will try again every second. This solution can in theory lead to starvation. But practically it shouldn’t.

 

So this is a safe operation but still is not recommended. It is better when different process on different machines write to different files and later some other system combine this data from many files into one target file (something like in “map-reduce” processing).

 

The only problem would be with simultaneous appending (writing at the end) to the same file by two clients.

 

Please also read a thread “Append and seek while writing functionality” on the group archive:

http://sourceforge.net/mailarchive/forum.php?forum_name=moosefs-users <http://sourceforge.net/mailarchive/forum.php?forum_name=moosefs-users&max_rows=25&style=ultimate&viewmonth=201006> &max_rows=25&style=ultimate&viewmonth=201006

 

 

Regards

Michał