Re: FreeBSD - "Experimentelle Features" - und Hackingtest

P.S.NFSv4 hat ein Delegation Feature aber ich wuesste nicht, wie ich das
beim Mounten als Verhalten angeben kann.

https://www.ietf.org/rfc/rfc3530.txt

1.4.6. Client Caching and Delegation
[...]

   The major addition to NFS version 4 in the area of caching is the
   ability of the server to delegate certain responsibilities to the
   client. When the server grants a delegation for a file to a client,
   the client is guaranteed certain semantics with respect to the
   sharing of that file with other clients. At OPEN, the server may
   provide the client either a read or write delegation for the file.
   If the client is granted a read delegation, it is assured that no
   other client has the ability to write to the file for the duration of
   the delegation. If the client is granted a write delegation, the
   client is assured that no other client has read or write access to
   the file.

   Delegations can be recalled by the server. If another client
   requests access to the file in such a way that the access conflicts
   with the granted delegation, the server is able to notify the initial
   client and recall the delegation. This requires that a callback path
   exist between the server and client. If this callback path does not
   exist, then delegations can not be granted. The essence of a
   delegation is that it allows the client to locally service operations
   such as OPEN, CLOSE, LOCK, LOCKU, READ, WRITE without immediate
   interaction with the server.

Ich bin gerade durch die CentOS manpage nfs(5) und konnte nichts finden.

FreeBSDs nfsv4(4) sagt Folgendes:

 If the file systems you are exporting are only being accessed via NFSv4
     there are a couple of sysctl(8) variables that you can change, which
     might improve performance.

     vfs.nfsd.issue_delegations
             when set non-zero, allows the server to issue Open
Delegations to
             clients. These delegations permit the client to manipulate the
             file locally on the client. Unfortunately, at this time, client
             use of delegations is limited, so performance gains may not be
             observed. This can only be enabled when the file systems being
             exported to NFSv4 clients are not being accessed locally on the
             server and, if being accessed via NFS Version 2 or 3 clients,
             these clients cannot be using the NLM.

     vfs.nfsd.enable_locallocks
             can be set to 0 to disable acquisition of local byte range
locks.
             Disabling local locking can only be done if neither local
             accesses to the exported file systems nor the NLM is
operating on
             them.

     Note that Samba server access would be considered ``local access'' for
     the above discussion.

Weiter unten zu CLIENT MOUNTS heisst es:

     If the NFSv4 server that is being mounted on supports delegations, you
     can start the nfscbd(8) daemon to handle client side callbacks. This
     will occur if

           nfsuserd_enable="YES"
           nfscbd_enable="YES"

     are set in rc.conf(5).

     Without a functioning callback path, a server will never issue Delega-
     tions to a client.

So.. es mag zwischen FreeBSD-Systemen funktionieren?

Es gruesst
Peter

Peter Ross wrote:
> Hallo,
>
> ich nochmal..
>
> Danke fuer alle Kommentare.
>
> Ich habe noch eine andere Frage: Ich suche ein schnelles "NFS", was wenig
> Overhead hat, weil auf Serverseite kein Locking notwenig ist und auch UIDs
> etc. keine Rolle spielen, es kann alles einfach "durchgereicht" werden.
>
> Hintergrund: Wenn man einen Fileserver mit reichlich Plattenplatz und RAM
> hat, und man Remotesysteme als "satellite" ohne grosse Resourcen und
> eigenes Dateisystem drauf arbeiten lassen will.
>
> Oder lokal nur sowas wie ein Log hat, der dann das auf das
> Remotefilesystem "durchreicht".
>
> Ganz grob gesagt, muesste das Filesystem nur
> - vom Netzwerk Dateien lesen koennen
> - die Aenderungen in ein Journal schreiben
> - das Journal ans Netzwerkfilesystem uebertragen
>
> Den Rest macht dann der Server (also Dateien bereitstellen und Aenderungen
> zurueckschreiben).
>
> Gibt es das?
>
> Es gruesst
> Peter
>
>
>
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Received on Tue 22 Sep 2015 - 02:03:47 CEST