[Info-vax] VMS defragmenters

[George Cook]

In article <paul.sture.nospam-0B3C00.15045716042009 at mac.sture.ch>, "P. Sture" <paul.sture.nospam at hispeed.ch> writes:
> In article <49e53f08$0$90264$14726298 at news.sunsite.dk>,
>  Arne Vajhøj <arne at vajhoej.dk> wrote:
> 
>>  decade or two ago there was Raxco PerfectDisk and Executive
>> DiskKeeper.
>> 
>> I used PD - it was pretty good.
>> 
>> There were also a freeware one on the DECUS tapes.
>> 
>> Google seems to indicate that it was called JUICER.
>> 
>> I don't think it was widely used. People preferred the commercial ones.
>> 
>> Then Digital released DFU/DFO and most people switched to that and
>> the other products more or less disappeared.
> 
> JUICER can be found on the OpenVMS Freeware V4 CD.
> 
> And going back further, there was a utility or driver which reduced 
> defragmentation in the first place.

The Acorn Fragmentation Avoider written by Glenn Everhart.  It should 
be on the OpenVMS Freeware V3 CD.  We still run it here on both VAX
and Alpha.  Although it was last updated in 1997, it works on Alpha
VMS V8.2 (needing nothing more than a relink after major VMS upgrades).

>From the readme:
----------------
The Fragmentation Avoider consists of an intercept driver and a
control utility which reduce the rate of VMS disk fragmentation
in two ways:

1. Files are extended in "contiguous best try" fashion, preventing
        the accumulation of many tiny extents in extent cache which
        would otherwise cause new files to be allocated in small
        bits.
2. Files are extended by a fraction of their current size when this is
        larger than the default, subject to minimum and maximum
        extents and to a constraint of never forcing the extent
        to be more than 1/8 of volume free space. Thus files tend
        to be extended less often and in larger pieces than by default
        which leads to their being far less fragmented than otherwise.

These actions are configurable on a per volume basis, and FragmentAvoid
can be enabled or disabled separately on any disk on a system.
----


George Cook
WVNET