On Tue, Sep 27, 2011 at 01:04:23PM +0200, Folkert van Heusden wrote: > > I'm interested in setting up a FUSE-like infrastructure in userspace that > > will > > use NBD and allow people to develop virtual block devices without having to > > write any kernel code. For example, one of the things I would like to do is > > create a deduplicating block device, and it would be easiest if I could > > Dedupping block device? Something like http://vanheusden.com/java/BlackHole/ ? > > > I have read about similar attempts and I know that there are deadlock issues > > associated with running NBD as a client and server on the same machine. So > > I was > > As far as I experienced this only happens with swap on nbd.
No, NBD can deadlock with filesystems on NBD too, though it's a different deadlock. There seems to be a common cache handling for all block devices; this can result in nbd-server waiting for another block device to flush its caches before it will be allowed to write to disk again. If that 'other device' is the block device that nbd-server is serving, you've got a deadlock. -- The volume of a pizza of thickness a and radius z can be described by the following formula: pi zz a ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 _______________________________________________ Nbd-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/nbd-general
