> P=E5 m=E5 , 04/10/2004 klokka 22:45, skreiv Steve Dickson:
>=20
> > 3) There is no user level support. I realize this is=20
> extremely cheesy
> > but I noticed that the NFS posix mount option (in the=20
> 2.6 kernel)
> > was no longer being used, so I high jacked it. Which means
> > to make NFS to used CacheFS you need to use the posix option:
> >=20
> > mount -o posix server:/export/home /mnt/server/home
>=20
> This is my one and only real gripe about it. The posix mount option i=
s
> clearly documented, so we really cannot play around with it. Why can'=
t
> you just add a separate cachefs flag?
probably ought to look like the Solaris UI here. isn't there a "cachef=
s" mount option on Solaris? anyway, reusing "posix" just for a prototy=
pe seems harmless enough.
> I'm a bit worried about the use of the raw IP address in
> nfs_cache_server_match(). It seems to me that when we add the NFSv4.1
> support for trunking over several different transport mechanisms (RDM=
A,
> IPv4/v6 etc) on the same mountpoint, then we may end up with a proble=
m.
> We can probably leave it in for now, but later we may want to conside=
r
> switching to using server->hostname or something equivalent.
yup, we want to avoid adding any transport specific detail in the NFS c=
lient, and leave that kind of stuff to the RPC client. good catch, tro=
nd.
i did a lengthy study of the AFS cache manager about a decade ago. int=
erestingly, the place where it really falls down is in recycling disk b=
locks for use with a new incoming file to be cached. the underlying ca=
che file system has to get rid of the on-disk data for old files before=
it can reuse the blocks for a new file. otherwise, the old data is ex=
posed if the new file maps in pages it hasn't written to yet. if the c=
ache is turning over quickly, handling this correctly can result in ser=
ious disk thrashing as the cache file system frees and erases blocks on=
disk and then reallocates them to the new file.
steve, is there [english] documentation somewhere that describes how th=
e cachefs works?
P=E5 ty , 05/10/2004 klokka 00:51, skreiv Lever, Charles:
> probably ought to look like the Solaris UI here. isn't there a "cach=
efs" mount option on Solaris? anyway, reusing "posix" just for a proto=
type seems harmless enough.
Mounting Solaris cachefs is very different. Their syntax is of the form=
:
mount -F cachefs [ generic_options ] -o backfstype=3Dfile_system=
_type [ specific_options ] [ -O ] special mount_point
So an example given on their manpage is as follows:
------
The following example CacheFS-mounts the file system
server1:/user2, which is already NFS-mounted on /usr/abc as
/xyz.
example# mount -F cachefs -o backfstype=3Dnfs,backpath=3D/usr/abc=
,
cachedir=3D/cache1 server1:/user2 /xyz
------
Cheers,
Trond