From: Matthew J. Zito (mzito@register.com)
Date: 03/16/01-09:43:54 PM Z
Message-Id: <a05010402b6d8822fc711@[24.29.132.249]> Date: Fri, 16 Mar 2001 22:43:54 -0500 From: "Matthew J. Zito" <mzito@register.com> Subject: Re: NFS MIB ideas At 5:33 PM -0800 3/16/01, Brent wrote: >"Matthew J. Zito" wrote: >> What if the mounting of a directory was treated >> as a directory-level lock? When the client mounts the directory, it >> could place a lock on the directory that simply indicates that it has >> it mounted. An umount request could remove the lock. Looking at the >> RFC, it looks as though the LOCK definition only allows for file >> locking. If it was modified to permit a directory entry also, the >> server could have information about which clients consider which >> directories mounted. > >You wouldn't want to lock a directory - just flag it in some >way to indicate that it is "in use". What do you do when the >client reboots and forgets which servers it had mounted when >it died? You could put a lease on the flag, but that would >require a client to periodically "ping" the server to keep >the lease alive - even when the mount wasn't in use. That >would be a bad idea. > >A better idea might be to have the server keep track of >which clients have used the filesystem "recently" and >give the sysadmin access to that information. No protocol >changes are required for that. > Mmm - I don't mean lock, as in "lock for writing", I mean a LOCK_RT on the directory itself - that would indicate to the server that the directory should be considered "mounted". The lock would be simply for informational purposes, and could be handled in the same way as any other lock. If a better way to do that would be to implement an "in use" flag, that would be fine - I was just thinking that doing this within the existing structure of the protocol would be useful. When a client reboots, the client has to have a knowledge of what filesystems to mount anyway - so it doesn't matter that it previously had it mounted - it'll just re-lock the directory when its mounted. Server-side access tracking would be equally useful, but would serve a different purpose. Any reasonable list of recently-accessed files on a per-client basis could quickly hide the filesystem information. The point of keeping track of mounts is to allow the server administrator to monitor who is mounting what directories and when, something that is very useful, and not available. Thanks, Matt -- Matthew J. Zito Systems Engineer Register.com, Inc., 11th Floor, 575 8th Avenue, New York, NY 10018 Ph: 212-798-9205 PGP Key Fingerprint: 4E AC E1 0B BE DD 7D BC D2 06 B2 B0 BF 55 68 99
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