(Shyh-Wei Luan) wrote:
>
> Hi,
>
> I am looking into a volume-migration solution for AFS/DFS. The idea
> is that volumes that are not accessed for a long time can be
> automatically migrated to on-line library, to alleviate on-line disk
> storage need to keep those dormant volumes (e.g., outdated tools, dead
> projects, absent user volumes, ...). These volumes shall be migrated
> back to disks automatically when they are referenced. Backup shall
> also be done on migrated volumes.
I would highly suggest that you review some background info on some
prototyped
solutions, like the "Multi-resident AFS System" that was done at
University of
Pittsburgh. (I believe it was even presented at Decorum (originally
known as the
AFS Users Group).
>
> I'd like to evaluate the merits of this approach, especially I need
> to know how many volumes out there are not accessed. The
> "vos examine" command gives the last update time but not the last
> access time to account for reads. I tried the volinfo command on file
> servers and it always gives a zero "accessDate". I guess it is not really
> used. It also gives a "dayUseDate". Would it be an accurate reference
> for the last access date???
I would highly advise that you look at AFS and DFS as separate entities.
One of the more notable differences is that unlike AFS, DFS does a
better
job with metadata, particularly things like atime, mtime, ctime. (It
would not be
able to deliver POSIX single site semantics, if it didn't)
Please do not limit the function of your system to what you empirically
observe with
AFS. Look at DFS, too!!!
>
> It is also a concern that some file backup, garbage collection, or
> virus checking programs might access these inactive volumes periodically,
> and make them look accessed. So, any volume access time reading may not
> be accurate in these environments.
It shouldn't be too difficult to work around some of this. Does it
really matter
whether there are anywhere from 1-10 accesses to a volume or fileset,
when others are
getting hit 1000's of times. If you loooked a statistical distribution
of the volume access,
it should be easy to ascertain a baseline for the adminstrative
overhead.
>
> Has this kind of measurement being done? How did you do it? What
> did you find? Do you think space management based on volumes might be
> useful to you?
Yes, it was done at the IBM Austin site. I'm sure it's been done at
other
places.
Regardless of the technique, volume (or fileset) archival and management
is
sorely needed. At Decorum it is probably one of the most frequently
requested items from
the file system user community.
--
Chris Cowan PSW Technologies
[EMAIL PROTECTED] Distributed Computing Systems
(512) 343-6666 x339 9050 Capital of Texas Hwy. North
(512) 345-4976 (fax) Austin, TX 78759
http://www.pswtech.com
