How long...?

[DrTeeth]

How long can one keep a full backup and keep on using it as a basis
for backups?

Currently, I do daily incrementals. Then the number of separate files
gets too great, I'd like to start again from the original base file.

Does IfW do integrity checking on the base file each time the first
changes only backup is made? In other words, if I can make the backup
with no errors does that mean that the base file is 100% good?
--
Cheers,

DrT

** You've never known happiness until you're married;
** but by then it is too late.

[mjnelson99]

Can you validate again?

Won't you lose the incrementals if you use the same base file later on?

On 10/9/2014 6:12 PM, DrTeeth wrote:
> How long can one keep a full backup and keep on using it as a basis
> for backups?
>
> Currently, I do daily incrementals. Then the number of separate files
> gets too great, I'd like to start again from the original base file.
>
> Does IfW do integrity checking on the base file each time the first
> changes only backup is made? In other words, if I can make the backup
> with no errors does that mean that the base file is 100% good?
>

[George]

The original full backup remains the same. It's just the baseline that
IfW uses to compare with the hard drive when determining what needs to
be backed up. You can reuse the original full backup as often as you want.
If you defrag a hard drive, then files get moved around so when you want
to do an incremental backup, the current state of the drive may be much
different than the original full backup. Hence, the incremental backup
may be large. Subsequent incrementals may be smaller depending on the
number of changes since the last incremental backup. (For those
interested, see Appendix B of the IfW 2.91 manual for backup strategies.)
I don't have any insight regarding the integrity of the original backup
unless a post-backup validation option is selected. Hopefully, TB can
chime in on this item.
Best,
George

On 10/9/2014 6:55 PM, MJNelson wrote:
> Can you validate again?
>
> Won't you lose the incrementals if you use the same base file later on?
>
> On 10/9/2014 6:12 PM, DrTeeth wrote:
>> How long can one keep a full backup and keep on using it as a basis
>> for backups?
>>
>> Currently, I do daily incrementals. Then the number of separate files
>> gets too great, I'd like to start again from the original base file.
>>
>> Does IfW do integrity checking on the base file each time the first
>> changes only backup is made? In other words, if I can make the backup
>> with no errors does that mean that the base file is 100% good?
>>
>
>

[TeraByte Support]

Each file is going to take up something like 2 to 4M of memory, so you don't
want to chain to get too long. Start a new one after a while.


yes, I believe all the normal checking is done.


"DrTeeth" wrote in message news:8734@public.image...

How long can one keep a full backup and keep on using it as a basis
for backups?

Currently, I do daily incrementals. Then the number of separate files
gets too great, I'd like to start again from the original base file.

Does IfW do integrity checking on the base file each time the first
changes only backup is made? In other words, if I can make the backup
with no errors does that mean that the base file is 100% good?
--
Cheers,

DrT

** You've never known happiness until you're married;
** but by then it is too late.

[TAC109]

On Thu, 9 Oct 2014 16:12:46 PDT, DrTeeth wrote:

>How long can one keep a full backup and keep on using it as a basis
>for backups?
>
>Currently, I do daily incrementals. Then the number of separate files
>gets too great, I'd like to start again from the original base file.
>
> Does IfW do integrity checking on the base file each time the first
>changes only backup is made? In other words, if I can make the backup
>with no errors does that mean that the base file is 100% good?

AIUI, it depends on the setting of the 'Speed up changes only backup'
option. If this is set, IFW just refers to the latest hash file to
determine the (hash of the) previous contents of each disk block. If
there are no hash files, then IFW needs to refer to the actual
previous image files to get this information, chaining back to the
starting 'full'.

[DrTeeth]

On Thu, 9 Oct 2014 21:10:32 PDT, just as I was about to take a herb,
Tom Cole disturbed my reverie and
wrote:

>AIUI, it depends on the setting of the 'Speed up changes only backup'
>option. If this is set, IFW just refers to the latest hash file to
>determine the (hash of the) previous contents of each disk block. If
>there are no hash files, then IFW needs to refer to the actual
>previous image files to get this information, chaining back to the
>starting 'full'.

I am only asking as I mirror the backup on my internal hard disk to an
external USB3 one. A full backup is about 300Gb so if I don't have to
create it too frequently, that will save loads of time.

Thanks to you and all who replied.
--
Cheers,

DrT

** You've never known happiness until you're married;
** but by then it is too late.