multiple smbd's ?

David Collier-Brown davecb at
Fri Jan 4 07:11:05 GMT 2002

R.Oehler at wrote:
> On 03-Jan-2002 David Collier-Brown wrote:
> > Ludolf Holzheid wrote:
> >> But samba *is* already spawning a seperate server for each
> >> connection. So what is Ralf asking for?
> >
> >       A pool of processes per client, so that if
> >       one blocks, another can continue.  This is
> >       one of a plethora of workarounds for an
> >       HSM thrashing.
> >
> Yes, exactly. When I do one copy from multiple clients to
> separate media (each copy's has it's own, separate medium as
> destination in the server's jukebox) then everything works
> fine.
> When I do just two copies from one client to two different
> server-media, then the copies of this client get stuck because
> there is only one server smbd for two only alternatingly
> accessible client-media.
> Are there solutions availlable?

	There are, almost by definition, a number of
	possible solutions to HSM thrashing.

	The obvious one is use a hierarchical storage
	manager that doesn't thrash (;-))  The ones I'm
	familiar with all have caches, which can be
	tuned to minimize the problem.

	The second approach is to have the application
	using the hsm to read the whole file, thus
	implicitly caching it.  This can be done
	in Samba, by writing a vfs module that issues
	a read larger than the expected file size.
	This will cache the data in a combination of
	memory and swap.

	The third is to use cachefs in front of the
	hsm. This assumes the OS has a vfsswitch and
	a caching filesystem.

	Applying the NFS-like solution of having a pool
	of service processes/threads/whatevers would
	require a **substantial** change to Samba, and
	provide only a moderate improvement, as it's
	basically a work-around, not a solution to the
	underlying problem.


David Collier-Brown,           | Always do right. This will gratify 
Americas Customer Engineering, | some people and astonish the rest.
SunPS Integration Services.    |                      -- Mark Twain
(905) 415-2849                 | davecb at

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