[mythtv-users] Is there a distributed filesystem available?

[Steve Hodge]

On 6/20/06, Brian Wood <beww at beww.org> wrote:
> On Jun 19, 2006, at 10:45 PM, Steve Hodge wrote:
> > RAID 5 gives you a high level of fault tolerance at the cost of
> > complexity and capacity. What Debabrata wants is a partially tolerant
> > setup, basically a file system that can span X disks, and when a disk
> > fails it only loses the files on the failed disk (i.e. 1/X of the data
> > if it were full). It's sort of in between RAID 0 and RAID 5: RAID 5
> > can have a single disk fail without any data loss, RAID 0 will lose
> > all data when a single disk fails, this hypothetical filesystem would
> > lose some but not all of the data if a disk fails.
>
> Wouldn't simple aggregation (sometimes known as "linear RAID)
> accomplish this? While it would take some specialized measures to
> recover the data on the remaining operational disks the data is not
> "interleaved" the way RAID0 data is (which makes it impossible to
> recover any files larger than a single block if it is partially on a
> failed disk). Also, some files would be non-contiguous, but if you
> used the filesystem just for writing and reading large video
> information files, and perhaps de-fragged often, you could probably
> recover a lot of the information if a single disk failed.

Yup, that's what I was thinking. But it could be much more robust if
the filesystem was aware of what was going on. Ideally I was thinking
of a "meta" filesystem that would use other filesystems for the actual
storage. I.e. you mount your various underlying drives, tell the meta
filesystem where they can be found and then mount that filesystem
wherever you want it. If one of the underlying filesystems vanishes
then the files stored on that particular filesystem would just
disappear as well.

Steve