Subject: [netatalk-admins] netatalk and nearline storage?
From: Mike Mansell (mansell@CIMtegration.COM)
Date: Wed Mar 11 1998 - 09:38:08 EST
> Unix directory lookup can be very slow. This is the big problem
> with news servers like INN which spend more time looking up files
> than it does reading them.
>
> In order to implment persistent directory ids, you'd have to do something
> like this. My idea would be to keep a single file and directory lookup
> cache. It's kept it up to date by verifying that the container directory
> hasn't been modified since a particular entry was made. It would be
> built "on-demand" as I occasionally mount a 200GB (!) store for use with
> netatalk, and I wouldn't want to have to pre-index that.
Being able to avoid massive pre-indexing and directory lookups would be a
life-saver for our installations. We plan to use netatalk in some setups
to allow Mac's access to our 100GB-1500GB NFS NearLine storage server
(nearline cuz its tape + disk cache, Network <---> Disk <---> Tape Array)
via a UNIX box. Because our storage server is nearline, and includes tape
drives, opening directories through netatalk can generate a whole bunch of
requests into the tape array to get the .parent and .appledouble files and
such! - it can be a real nightmare (esp. if it preempts someone trying to
get to an actual file!). If the '.' files are in the disk cache though,
its not too bad, but still theres a lot of network chatter just opening
dir's. If a single indexing file could hold info. for many other files,
it would at least speed up the number of files netatalk has to open and
close - but I know this won't happen overnight. For now, I think we'll
just have to add in someway to 'lock' the .parent and .appledouble files
into the disk cache (so our tape array doesn't have a heart attack!).
Maybe my first question should have been, "has anyone had experience with
netatalk and nearline storage?".
Mike.
--
/\ Michael G. Mansell, BSc. (SCS) Office: (416) 665-0767 x228
/\ \ Engineering Support Services clearNET:(416) 984-7839
/\ \ \ DataVation Inc., Toronto Fax: (416) 665-8285
/ \ \ \ WWW.DataVation.COM Email: MikeM@DataVation.COM
This archive was generated by hypermail 2b28 : Sat Dec 18 1999 - 16:31:27 EST