some hopefully heavy mogilefs development

[Mark Smith]

> Hi, my company is goinging to launch MogileFS within 1 months, I have done
> serveral tests with the CVS version, I also did some patches to the CVS
> code to solve of large-file and memory leak issues, 'coz the company is
> really paranoid of stability, they also want mysql-cluster, which looks
> scary to me. Right now, I'm pretty confident with CVS code+my patches,
> just want to know:
> 
> 1. Which one is more stable, from SVN or CVS ?

I have never seen 2.0 crash.  However, it's definitely not as battle tested
as the CVS/1.0 version.  If you're more comfortable going with the older
one until we've had more experience with the new one, that's your call.  If
your company is really paranoid, that's probably better.

> 2. Is it hard to migrate data from CVS version to SVN version in the future ?

The database formats are nearly identical and you can run both versions at
the same time, actually.  You don't have to touch the files on the storage
nodes at all, nor do you have to do any real work on the database.  We've
added one or two more tables, but haven't changed any existing ones.

So no, migration is not hard.

> 3. Are there important bugs on the CVS code fixed in SVN ?

There are a lot of improvements.  For example, CVS code has issues with
sometimes the tracker locks up if the database goes away and you have to
restart it.  (All of the query worker threads get locked.)

The SVN version has a watchdog in place that automatically kills off any
child that hasn't reported in after a certain amount of time (varies by
job).  So - even if it runs into a query that kills the workers or the
database goes away or something, the SVN version recovers from the problem
without a restart.

The replication system in the SVN version is also rewritten to be more
efficient.  It handles errors much better, too.

Lots of changes.  2.0 is superior to 1.0 but if you're not comfortable
running relatively new software, 1.0 isn't a bad option.


--
Mark Smith
junior at danga.com