[Info-vax] simple HBVS question

[Robert A. Brooks]

On 10/19/2011 12:58 PM, Phillip Helbig---undress to reply wrote:
> Now that I have set up HBMM on some shadow sets, the bitmaps are zeroed
> some time after the threshold is reached.  The lower the threshold, the
> faster the MM, though of course there are disadvantages from having the
> threshold too low; in particular, any reasonable value for the threshold
> will allow a MM to take place much more quickly than with an infinite
> threshold, at least for a disk whose content gets completely recycled.

> Does this mean that a shadow COPY will also take place more quickly
> (assuming that conditions are such that a minicopy can be performed)?

No, other than the multiuse bitmaps (which were added post-7.3-2 and I 
don't think were backported), HBMM and minicopy bitmaps are completely 
separate.

You can experiment to see how long a merge (either full or mini) will 
take by using $SET SHADOW /DEMAND_MERGE to force a merge.  My guess is 
that you'll be shocked at how quickly an HBMM will finish.

                               -- Rob