What does validate option "Multi-pass" do?

[pimjoosten]

When validating in IFW there is a validate option "Multi-Pass". I cannot find an explanation of this option anywhere (incl. the latest manual). What does this option do?

I think it is a good idea to include an explanation in the manual, especially because all other validate options are explained.

[Bob Coleman]

pimjoosten wrote:
> When validating in IFW there is a validate option "Multi-Pass". I
> cannot find an explanation of this option anywhere (incl. the latest
> manual). What does this option do?

This is only relevant (and only available) if the thing being validated is an incremental or differential (changes only) backup. I don't know the internal logic, but if Multi-Pass is not selected, the file being validated, the original base file, and any relevant previous incremental backups will all be validated in a single pass. If Multi-Pass is selected each of the above mentioned files will be processed in a separate pass. Again, I don't know the internal logic, but if Multi-Pass is selected, one will be able to see each relevant file processed one after the other.

If there is any value in using Multi-Pass, I don't know what it is.

[Brian K]

Bob Coleman wrote:
> pimjoosten wrote:
> > When validating in IFW there is a validate option "Multi-Pass". I
> > cannot find an explanation of this option anywhere (incl. the latest
> > manual).

pimjoosten,

I just looked in the IFW manual (ver 3.38) and there is a good explanation of Multi-pass.

[Bob Coleman]

For whatever it's worth note that Multi-Pass is available when restoring as well as when validating and, as I just discovered, even when creating a backup though it appears to not have the same function there.

[pimjoosten]

Thanks Bob and Brian for responding.

Brian K wrote:
> Bob Coleman wrote:
> > pimjoosten wrote:
> > > When validating in IFW there is a validate option "Multi-Pass". I
> > > cannot find an explanation of this option anywhere (incl. the latest
> > > manual).
>
> pimjoosten,
>
> I just looked in the IFW manual (ver 3.38) and there is a good explanation of
> Multi-pass.

Could you please point me to that explanation? On page 108/109 under the heading Validation Options I do not see it. I do see it under Setting Backup Options on page 57 and Restore Options on page 99, but not for Validation Options. Please note, as Bob Coleman wrote, that Multi-Pass is available for backing up, restoring and validating. But Multi-Pass has a different meaning for backing up and restoring. That is why my question is: what is its meaning for validating? Most importantly: what is its purpose? Logical reasoning leads me to the assumption it is the same as for restoring (only useful when the full and change only backups are on different media, e.g. DVD's), but it would be better to know whether that is true and not having to assume.

[Brian K]

pimjoosten,

I don't have a Validate Multi-Pass option. My Backups/Restores are multi partition.

[Bob Coleman]

I do have a Multi-Pass option that can be selected when Validating. Must be validating a changes only backup.

I also now see that Multi-Pass is indeed not explicitly described for Validate. I'm reasonably convinced that the function is the same as for Restore.

[pimjoosten]

Thanks Brian and Bob,

Apologies for my late reply. My backups and restores are also multi partition. But as Bob said, the Multi-Pass option is only shown when validating a changes only backup. I agree with Bob that the function likely is the same as for restore, i.e. the full backup is validated first and then all consecutive backups. Like with restore, this option only has value when the backups are stored on removable media (CD/DVD/BD).

@Terabyteunlimited: It would be a good idea to include this validate option in the manual for completeness sake. It is not yet included in v2020-04-18 of the manual.