Disable read/write caching to disk?

[Scott Long]

Garrett Wollman wrote:

> <<On Thu, 26 May 2005 22:03:39 -0600, Scott Long <scottl at samsco.org> said:
> 
> 
>>is just as much work as porting GFS, if not more, since UFS/FFS is 
>>closely tied to the buffer cache and block layers on BSD, and divorcing
>>probably would be quite difficult.
> 
> 
> For multiple writers, probably so.  For the single-writer case, I
> don't think so, since the readers can mount a snapshot while the
> writer mounts the read-write view.

Well, having a writer is pointless if the readers are stuck on a 
snapshot.  Also, I'm not exactly sure how dirty buffers get flushed
to disk in the case of a snapshot.  Recall that the snapshot file
only save the deltas of the old data, and flushing those deltas to
disk is still under the control of the VM/buffer/cache system.  You'd
probably still have to have some sort of inter-computer synchronization
system in place.

> 
> All this would be a lot easier if we had a storage manager more like
> ZFS's.
> 

Well, ZFS doesn't really exist yet, so it's hard to draw a comparison ;-)

Scott