Re: XFS and JFS in RH4?

[Arjan van de Ven <arjan infradead org>]

On Sun, 2005-06-26 at 19:50 -0700, Don MacAskill wrote:
> Not all of us have been using RHEL for the lifetime of our company or 
> linux servers.
> 
> It would be nice when we want to migrate from SuSE or some other Linux 
> flavor to at least use those partitions, rather than coming up with 
> complicated migration mechanisms.
> 
> We have 100TB+ of data, for example.  Luckily, I migrated from SuSE to 
> RHEL early in our life and only have a few TB in XFS, but those few TB 
> are a royal pain.  If I hadn't already migrated, Red Hat's stance on XFS 
> means we couldn't migrate, even if we wanted to.  SuSE has essentially 
> obtained vendor lock-in for anyone who has difficult-to-move XFS 
> partitions, regardless of other feature and support comparisons.


XFS is a problematic case though. It requires 8Kb stacks (and not the
RHEL default 4K stacks), which in turn makes the VM less robust (a lot
of the RHEL3 VM issues originate in the area of > 4Kb allocations, of
which stacks are one of the major causes. With 4Kb stacks (and other 2.6
fixes) this problem is virtually non-existant anymore meaning the VM is
in far less trouble and needs less hacks, which then break less). It
also reduces the number of (java) threads you can have *for everybody*,
not just XFS users. Reducing the features/quality of RHEL4 for something
unsupported that affects a minority of customers is just a really bad
tradeoff to make.