Re: Storage space smarts

[Bob Durst]

>Dean Brissinger writes:
>
>>On a side note, does Retrospect check for identical files
>>between backup clients?  I have 30 macs with identical system
>>folders.  I really only need to backup those system files once.  If
>>retrospect was so smart, I could do full backups site wide and get
>>most efficient coverage with minimal tape space.  I note it tends to
>>backup more than it needs to because of volume name, time stamp, etc.
>
>Alas, there are files that change their time stamp any time they are
>accessed. Retrospect has no choice but to back them up unless you use an
>exclude filter.

Is there (or could there be) a filter that allows one to exclude a 
file based on ONLY a changed date/time stamp? Or maybe better still 
one that did a further compare (checksum or ...) to decide that it 
was ok to skip a particular file because it really was backed up 
already.
-- 
-Bob D.
Builder and Pilot of Kinetic Sculpture Vehicle "Killer Tomato"
Visit my web site (http://www.bcc.orst.edu/~durstb/ )for pictures and 
additional info. 



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Re: Storage space smarts

[Daniel Knight]

Dean Brissinger writes:

>On a side note, does Retrospect check for identical files 
>between backup clients?  I have 30 macs with identical system 
>folders.  I really only need to backup those system files once.  If 
>retrospect was so smart, I could do full backups site wide and get 
>most efficient coverage with minimal tape space.  I note it tends to 
>backup more than it needs to because of volume name, time stamp, etc.

Alas, there are files that change their time stamp any time they are 
accessed. Retrospect has no choice but to back them up unless you use an 
exclude filter.

Dan Knight, information systems manager   [EMAIL PROTECTED]
Baker Book House Company 
6030 East Fulton   616-676-9185 x146
Ada, Michigan 49301 fax 616-676-9573

 - Macintosh: Love bug resistant, always Y2K ready



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Re: Storage space smarts

[Matthew Tevenan]

Dean,

Here's the procedure Retrospect goes through when deciding whether to copy
files:

Scan drive
Compare files scanned with backup set.
Mark files that have changed/are new.
Copy files...

Note I said "compare...with backup set." Retrospect does a file-by-file
compare, meaning it compares the FILES on your drive to the FILES on your
backup set. No matter what drive or computer they were originally backed up
on.

That said, it's doubtful your 30 System Folders are exactly identical. To
test this, try a backup of a System Folder to a new or recycled backup set.
Now, start an immediate backup, matching enabled, of another System Folder.
Don't start the backup but click Preview. (Alternatively, you may be able to
browse a System Folder in Configure>Volumes, select all, browse another
System Folder, and paste.) All checked files without diamonds next to them
are different and will be copied. You can get info/properties on any file in
a Browser, so if there are specific files you think Retrospect should not
want to copy, take a closer look...

Matthew Tevenan
Technical Support Specialist
Dantz Development Corporation
925.253.3050 
[EMAIL PROTECTED]

> From: Dean Brissinger <[EMAIL PROTECTED]>
> Reply-To: "retro-talk" <[EMAIL PROTECTED]>
> Date: Thu, 29 Jun 2000 10:32:22 -0600
> To: "retro-talk" <[EMAIL PROTECTED]>
> Subject: Re: Storage space smarts
> 
> On a side note, does Retrospect check for identical files
> between backup clients?  I have 30 macs with identical system
> folders.  I really only need to backup those system files once.  If
> retrospect was so smart, I could do full backups site wide and get
> most efficient coverage with minimal tape space.  I note it tends to
> backup more than it needs to because of volume name, time stamp, etc.
> 
> 
> At 3:49 AM -0700 06/29/00, Ming-Li wrote:
>> Hi Matthew,
>> 
>>> Retrospect uses several matching criteria to compare files
>>> that have already been backed up to what is about to be backed
>>> up. If one of the following has been changed at all,
>>> Retrospect will back up the file again:
>>> 
>>> MAC files:
>>> name, size, type, creator, creation date and time,
>>> modify date and time, and label.
>>> 
>>> PC files:
>>> name, size, modify date and time, file system.
>> 
>> Have you ever consider using something even more accurate as the
>> criterion--say, CRC32, or some sort of file signature? Will it
>> slow down Retrospect significantly than the current approach?
>> 
>> I'm asking because I've found many different applications put
>> same version of system files (dll and such) with different
>> date/time. The file name, size and version no. (by checking the
>> file's properties) stay the same, and a binary comparison would
>> show the two files are identical. They have touched the
>> date/time probably because they want all their files to have the
>> same date/time, or because the original software development
>> package (MS C++, Delphi, etc.) did so. And some other software
>> would make the date/time of its installation the date/time of
>> all the files it put in, regardless their original date/time.
>> 
>> Under current design, Retrospect would back those files up
>> again.  By way of CRC32 check, Retrospect would find those files
>> are indeed identical to the original ones and skip them.  It
>> would not only save storage space, but also give me extra
>> confidence for whenever I catch some new application overwriting
>> my system files, I can look in Retrospect's backup preview
>> window and find which of them are in fact identical (hence no
>> worry) and which are different (so I might have to restore my
>> backed up version to see which one is in fact newer).
>> 
>> I don't know if any application would change a file's content
>> without changing its date/time and size.  But if that happens, a
>> CRC32 check would expose them, too.
>> 
>> --
>> Best regards,
>> Ming-Li
>> 
>> 
>> 
>> 
>> --
>> --
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> 
> 
> 
> -- 
> . . . . . . . . ooo . . . . ooo . . . . . . . . .
> .   .
> .Dean Brissinger - Systems Administrator.
> .   Direct: 303-583-0278   Main: 303-444-0094   .
> .   Fax: 303-444-0470  http://www.vexcel.com/   .
&

Re: Storage space smarts

[Dean Brissinger]

On a side note, does Retrospect check for identical files 
between backup clients?  I have 30 macs with identical system 
folders.  I really only need to backup those system files once.  If 
retrospect was so smart, I could do full backups site wide and get 
most efficient coverage with minimal tape space.  I note it tends to 
backup more than it needs to because of volume name, time stamp, etc.


At 3:49 AM -0700 06/29/00, Ming-Li wrote:
>Hi Matthew,
>
>>  Retrospect uses several matching criteria to compare files
>>  that have already been backed up to what is about to be backed
>>  up. If one of the following has been changed at all,
>>  Retrospect will back up the file again:
>>
>>  MAC files:
>>  name, size, type, creator, creation date and time,
>>  modify date and time, and label.
>>
>>  PC files:
>>  name, size, modify date and time, file system.
>
>Have you ever consider using something even more accurate as the
>criterion--say, CRC32, or some sort of file signature? Will it
>slow down Retrospect significantly than the current approach?
>
>I'm asking because I've found many different applications put
>same version of system files (dll and such) with different
>date/time. The file name, size and version no. (by checking the
>file's properties) stay the same, and a binary comparison would
>show the two files are identical. They have touched the
>date/time probably because they want all their files to have the
>same date/time, or because the original software development
>package (MS C++, Delphi, etc.) did so. And some other software
>would make the date/time of its installation the date/time of
>all the files it put in, regardless their original date/time.
>
>Under current design, Retrospect would back those files up
>again.  By way of CRC32 check, Retrospect would find those files
>are indeed identical to the original ones and skip them.  It
>would not only save storage space, but also give me extra
>confidence for whenever I catch some new application overwriting
>my system files, I can look in Retrospect's backup preview
>window and find which of them are in fact identical (hence no
>worry) and which are different (so I might have to restore my
>backed up version to see which one is in fact newer).
>
>I don't know if any application would change a file's content
>without changing its date/time and size.  But if that happens, a
>CRC32 check would expose them, too.
>
>--
>Best regards,
>Ming-Li
>
>
>
>
>--
>--
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-- 
. . . . . . . . ooo . . . . ooo . . . . . . . . .
.   .
.Dean Brissinger - Systems Administrator.
.   Direct: 303-583-0278   Main: 303-444-0094   .
.   Fax: 303-444-0470  http://www.vexcel.com/   .
.   .
. . . . . . . oOOo . . A . . oOOo . . . . . . . .
  0 0
 '


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Re: Storage space smarts

[Ming-Li]

Hi Matthew,

> Retrospect uses several matching criteria to compare files
> that have already been backed up to what is about to be backed
> up. If one of the following has been changed at all,
> Retrospect will back up the file again:
>
> MAC files:
> name, size, type, creator, creation date and time,
> modify date and time, and label.
>
> PC files:
> name, size, modify date and time, file system.

Have you ever consider using something even more accurate as the
criterion--say, CRC32, or some sort of file signature? Will it
slow down Retrospect significantly than the current approach?

I'm asking because I've found many different applications put
same version of system files (dll and such) with different
date/time. The file name, size and version no. (by checking the
file's properties) stay the same, and a binary comparison would
show the two files are identical. They have touched the
date/time probably because they want all their files to have the
same date/time, or because the original software development
package (MS C++, Delphi, etc.) did so. And some other software
would make the date/time of its installation the date/time of
all the files it put in, regardless their original date/time.

Under current design, Retrospect would back those files up
again.  By way of CRC32 check, Retrospect would find those files
are indeed identical to the original ones and skip them.  It
would not only save storage space, but also give me extra
confidence for whenever I catch some new application overwriting
my system files, I can look in Retrospect's backup preview
window and find which of them are in fact identical (hence no
worry) and which are different (so I might have to restore my
backed up version to see which one is in fact newer).

I don't know if any application would change a file's content
without changing its date/time and size.  But if that happens, a
CRC32 check would expose them, too.

-- 
Best regards,
Ming-Li




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Re: Ans: Storage space smarts + new?

[Matthew Tevenan]

Bob,

> New related question: Is there a FAQ about how any of these criteria
> are set?

No. If Retrospect is reporting that it is about to back up files you know
have not changed since your last backup, take a closer look at a sample
file. Choose a file and start a restore by search for that file. When you
get to the final window (you don't actually have to do the restore), click
Files Chosen and Get Info or Properties on the most recent version of the
file on the backup. Print or take a screenshot of this window.

Now, go to the Configure tab from the Retrospect Directory and click
Volumes. Choose the volume the file is on and click Browse. Find the file in
question and Get Info or Properties on it. Put the two windows side by side
and look for even the slightest difference in any of the criteria I listed
above. 

Many things can cause a change in a file, even if the file has not been
accessed by the user. The operating system, as well as applications, are
constantly making changes to files. Further, whenever you change time zones
in the Date & Time control panel, your creation and modify dates are offset.
We have also found an issue in Mac OS 8.1 with HFS+ formatted volumes where
changing the Daylight Savings Time setting offsets the creation and modify
dates of all files.

There is also an issue where AppleShare might make a time translation when
connecting to another machine whose time is off by more than a certain
number of minutes. This time translation would also offset the creation and
modify dates of all files. I have also seen this happen when upgrading
operating systems, transferring files to different machines, or doing a
complete restore of data with Retrospect.

If you copy a file from a Mac to a PC, Retrospect will recopy it.

Please call us if you have any more questions.

Matthew
Technical Support Specialist
Dantz Development Corporation
925.253.3050 
[EMAIL PROTECTED]

> From: Bob Durst <[EMAIL PROTECTED]>
> Reply-To: "retro-talk" <[EMAIL PROTECTED]>
> Date: Wed, 28 Jun 2000 14:19:50 -0700
> To: "retro-talk" <[EMAIL PROTECTED]>
> Subject: Ans: Storage space smarts + new?
> 
> Thanks for the 'smart' reply. Glad to see there is some good sense in RS.
> 
> New related question: Is there a FAQ about how any of these criteria
> are set? For instance: if file A1 was created on computer 1 and then
> copied to computer 2 will it meet the 'already backed up criteria' or
> will the modify date and time be altered or creation date be
> different? I wouldn't expect any of the criteria to have changed in
> the above scenario.
> Does this scenario change if both 1 and 2 are Mac's vs PC's? How
> about if the file is created on Mac 1 then copied to PC 2?
> 
>> Bob,
>> 
>> Retrospect uses several matching criteria to compare files that have already
>> been backed up to what is about to be backed up. If one of the following has
>> been changed at all, Retrospect will back up the file again:
>> 
>> MAC files:
>> name, size, type, creator, creation date and time, modify date and time, and
>> label.
>> 
>> PC files:
>> name, size, modify date and time, file system.
>> 
>> Therefore if the A1 files are identical in all of the ways listed above,
>> there should only be one in your backup set if matching is set to its
>> defaults.
>> 
>> Matthew Tevenan
>> Technical Support Specialist
>> Dantz Development Corporation
>> 925.253.3050
>> [EMAIL PROTECTED]
>> 
>>> From: Bob Durst <[EMAIL PROTECTED]>
>>> Reply-To: "retro-talk" <[EMAIL PROTECTED]>
>>> Date: Wed, 28 Jun 2000 13:14:36 -0700
>>> To: [EMAIL PROTECTED]
>>> Subject: Storage space smarts
>>> 
>>> I'm curious as to how smart RS is about storage space on a backup
>>> set. I'll outline the simple situation for the experts to explain to
>>> me how RS handles it.
>>> 
>>> Computer 1 contains files: A1, B1, C1
>>> Computer 2 contains files: A1, B2, C1
>>> 
>>> Both are being backed up to the same backup set. In the backup set
>>> will there be two copies of A1, and C1 and one each of B1, and B2, or
>>> will there only be a single copy of A1 and C1 with pointers in both
>>> computers file lists that they each contain A1 and C1 but 1 contains
>>> B1 and 2 contains B2?
>>> 
>>> I wouldn't care if the files were small, but if they are BIG it makes
>>> a difference.
>>> --
>>> -Bob D.
>>> Builder and Pilot of Kinetic Sculpture Vehicle "Killer Tomato"
>>> Visit my web site (http://www.bcc.orst.edu/~durstb/ )for pictures and

Re: Storage space smarts

[Matthew Tevenan]

Bob,

Retrospect uses several matching criteria to compare files that have already
been backed up to what is about to be backed up. If one of the following has
been changed at all, Retrospect will back up the file again:

MAC files:
name, size, type, creator, creation date and time, modify date and time, and
label. 

PC files:
name, size, modify date and time, file system.

Therefore if the A1 files are identical in all of the ways listed above,
there should only be one in your backup set if matching is set to its
defaults.

Matthew Tevenan
Technical Support Specialist
Dantz Development Corporation
925.253.3050 
[EMAIL PROTECTED]

> From: Bob Durst <[EMAIL PROTECTED]>
> Reply-To: "retro-talk" <[EMAIL PROTECTED]>
> Date: Wed, 28 Jun 2000 13:14:36 -0700
> To: [EMAIL PROTECTED]
> Subject: Storage space smarts
> 
> I'm curious as to how smart RS is about storage space on a backup
> set. I'll outline the simple situation for the experts to explain to
> me how RS handles it.
> 
> Computer 1 contains files: A1, B1, C1
> Computer 2 contains files: A1, B2, C1
> 
> Both are being backed up to the same backup set. In the backup set
> will there be two copies of A1, and C1 and one each of B1, and B2, or
> will there only be a single copy of A1 and C1 with pointers in both
> computers file lists that they each contain A1 and C1 but 1 contains
> B1 and 2 contains B2?
> 
> I wouldn't care if the files were small, but if they are BIG it makes
> a difference.
> -- 
> -Bob D.
> Builder and Pilot of Kinetic Sculpture Vehicle "Killer Tomato"
> Visit my web site (http://www.bcc.orst.edu/~durstb/ )for pictures and
> additional info. 
> 
> 
> 
> --
> --
> To subscribe:[EMAIL PROTECTED]
> To unsubscribe:  [EMAIL PROTECTED]
> Archives:<http://list.working-dogs.com/lists/retro-talk/>
> Problems?:   [EMAIL PROTECTED]
> 



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Storage space smarts

[Bob Durst]

I'm curious as to how smart RS is about storage space on a backup 
set. I'll outline the simple situation for the experts to explain to 
me how RS handles it.

Computer 1 contains files: A1, B1, C1
Computer 2 contains files: A1, B2, C1

Both are being backed up to the same backup set. In the backup set 
will there be two copies of A1, and C1 and one each of B1, and B2, or 
will there only be a single copy of A1 and C1 with pointers in both 
computers file lists that they each contain A1 and C1 but 1 contains 
B1 and 2 contains B2?

I wouldn't care if the files were small, but if they are BIG it makes 
a difference.
-- 
-Bob D.
Builder and Pilot of Kinetic Sculpture Vehicle "Killer Tomato"
Visit my web site (http://www.bcc.orst.edu/~durstb/ )for pictures and 
additional info. 



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Ans: Storage space smarts + new?

[Bob Durst]

Thanks for the 'smart' reply. Glad to see there is some good sense in RS.

New related question: Is there a FAQ about how any of these criteria 
are set? For instance: if file A1 was created on computer 1 and then 
copied to computer 2 will it meet the 'already backed up criteria' or 
will the modify date and time be altered or creation date be 
different? I wouldn't expect any of the criteria to have changed in 
the above scenario.
Does this scenario change if both 1 and 2 are Mac's vs PC's? How 
about if the file is created on Mac 1 then copied to PC 2?

>Bob,
>
>Retrospect uses several matching criteria to compare files that have already
>been backed up to what is about to be backed up. If one of the following has
>been changed at all, Retrospect will back up the file again:
>
>MAC files:
>name, size, type, creator, creation date and time, modify date and time, and
>label.
>
>PC files:
>name, size, modify date and time, file system.
>
>Therefore if the A1 files are identical in all of the ways listed above,
>there should only be one in your backup set if matching is set to its
>defaults.
>
>Matthew Tevenan
>Technical Support Specialist
>Dantz Development Corporation
>925.253.3050
>[EMAIL PROTECTED]
>
>>  From: Bob Durst <[EMAIL PROTECTED]>
>>  Reply-To: "retro-talk" <[EMAIL PROTECTED]>
>>  Date: Wed, 28 Jun 2000 13:14:36 -0700
>>  To: [EMAIL PROTECTED]
>>  Subject: Storage space smarts
>>
>>  I'm curious as to how smart RS is about storage space on a backup
>>  set. I'll outline the simple situation for the experts to explain to
>>  me how RS handles it.
>>
>>  Computer 1 contains files: A1, B1, C1
>>  Computer 2 contains files: A1, B2, C1
>>
>>  Both are being backed up to the same backup set. In the backup set
>>  will there be two copies of A1, and C1 and one each of B1, and B2, or
>>  will there only be a single copy of A1 and C1 with pointers in both
>>  computers file lists that they each contain A1 and C1 but 1 contains
>>  B1 and 2 contains B2?
>>
>>  I wouldn't care if the files were small, but if they are BIG it makes
>>  a difference.
>>  --
>>  -Bob D.
>>  Builder and Pilot of Kinetic Sculpture Vehicle "Killer Tomato"
>>  Visit my web site (http://www.bcc.orst.edu/~durstb/ )for pictures and
>>  additional info.
>>
>>
>>
>>  --
>>  --
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>>  Archives:<http://list.working-dogs.com/lists/retro-talk/>
>>  Problems?:   [EMAIL PROTECTED]
>>
>
>
>
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-- 
-Bob D.
Builder and Pilot of Kinetic Sculpture Vehicle "Killer Tomato"
Visit my web site (http://www.bcc.orst.edu/~durstb/ )for pictures and 
additional info. 



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