Learn how to a build a cloud-first strategyRegister Now

x
?
Solved

Overwrite or Append on differential Backups?

Posted on 2006-05-10
7
Medium Priority
?
2,196 Views
Last Modified: 2008-01-09
I am using Microsoft Backup to backup the Documents and Settings folder and an application folder to an NAS drive. I created a baseline backup using the Normal method and then set a "Differential backup" to a different file name telling it to overwrite each time.

That seems to be working but I got to thinking....

What if there are files that change less often than the backups. If I have a file that gets backed up on the differential for say three or four nights, and then doesn't change for a few days. Does using the overwrite option mean that the file in question would not be backed up?

What is the best way to provide a good backup without creating a bunch of little files that I would need to restore individually in the event of a failure?
0
Comment
Question by:RandyTippetts
  • 3
  • 2
  • 2
7 Comments
 
LVL 16

Expert Comment

by:glenn_1984
ID: 16653240
The BEST way to backup and know that you only need to restore from a single location is to OVERWRITE the entire backup each time it runs.

Assuming you have enough drive space or tapes AND you can run this after hours, the fact that it takes longer is not important.

Differential backup IMHO is useless when you need to restore.
0
 
LVL 1

Author Comment

by:RandyTippetts
ID: 16653313
I prefer that option as well but I have 40gig of info being backup up on this server and several other automated backups running at night on the network. The longer each of them take the more they cut in to the off time which in our case is less than four hours. Even copying the folders to another location on the drive to be backed up during the active part of the day takes a considerable amount of time. Using the differential backup reduced that to between 15 seconds and three minutes.

I am hoping that there is some combination that will make them useful.
0
 
LVL 16

Expert Comment

by:glenn_1984
ID: 16654136
1...
Can you go to a DLT tape drive. That can hold lots of data.

or 2....
Also, you could backup Documents and Settings to the local PC....daily, then just copy it to the server once a week or so.
That way you have two simultaneous backups and  less network traffic.

0r 3...
For \documents and settings\ you could also automate
xcopy "c:\documents and settings\*.*"  "drive_letter:\\documents and settings\*.* " /y /s /d

That will overwrite file automatically, include subdirectories and only copy files with a newer date stamp.

Put it in a batch file and into the PC Scheduled tasks.
0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 
LVL 1

Expert Comment

by:-Garren-
ID: 16654967
Whoa... Randy, the reason for backups is to provide for fault-tolerance first, incidental restore second.

First question you should ask yourself is "How painful would it be if I lost my entire hard drive?" If your pucker factor just maxed out, then you should rethink your process.

Backups should always be moved OFF disk to another location. That way, if your disk dies during the week, it does not kill your differential backups located on the same disk.

Full backups means just that... everything on your system (and should include system state). Fulls reset (turns off) the archive bit on every file backed up.
Incremental backs up the files changed since the last backup and resets the archive bit (turns it off) on files it backs up.
Differential backs up the files changed since the last backup BUT DOES NOT RESET THE ARCHIVE BIT. So it collects ALL the files from the last FULL backup. These backups grow in size over the week or month.

Best practice is to keep one Full backup and at least the last two full Diffs. So you could erase the second to the last Diff file every time but not the last. This way, if the system were to die in the middle of the Diff backup, you didn't erase your last Diff. Then you can restore your last full and your last Diff and be right back to sqare.

BTW... are you backing up a workstation or a server? If its a server, you should be backing up the system state as well. Plus... if your using Win2k3 then you can use Snapshot restores for incidental restore of deleted/lost files.

Hope that helps


So....
0
 
LVL 1

Author Comment

by:RandyTippetts
ID: 16668434
The reason I copy the data to another spot on the drive is to provide a static dataset that I can backup during active periods. I am trying to develop a backup strategy for both servers and workstations using NT backup. I have Novastor Novanet for some of my servers now but they don’t allow you to backup to a network NAS. My data is getting too large for the DAT drives we have on the servers.

I have decided to run a primary “normal” backup weekly and follow up with differential backups nightly. My confusion is with the append or overwrite option on the differential backup. What am I gaining or loosing with each? What are the dangers?
0
 
LVL 1

Accepted Solution

by:
-Garren- earned 1200 total points
ID: 16668801
Then you already know that an append will create one file that grows a lot but does not eliminate the previous data. Overwrite will remove your last diff backup. Append is fine when you have plenty of disk space. Overwrite will save you disk space at the cost of fault-tolerance (redundant backups).

Additionally, append allows you to stream several diff backups to the same file... i.e. \docs then \databse then System State... etc. It is also possible to run the ntbackup from a batch file that will allow you to script different file names for your diff backups depending on the day of the week. That way, if you have enough disk space, you can simply script out an entire weeks worth of backups. Of course, you could also use the backup scheduler as well to do the same thing. With the scripts, you could right a scipt that will change the name of the file each time you backup and delete the files that are older than say 2 weeks prior to current day.

More directly... overwrite is risky since your removing the backups for the week prior to starting the current backup. If the system should die, your left with the last full backup. Append retains previous backups for the week but takes a lot of space on disk.

Hope that helps...
0
 
LVL 1

Author Comment

by:RandyTippetts
ID: 16670110
All good points. I think as far as having the storage space in concerned, it it better to do what you need to do to make the storage space available. I am going to go with append for a while on a weekly schedule and see what it does to my storage.

Thanks all.
0

Featured Post

Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This may not be a text book method to resolve VSS backup issues but it seemed to have worked on few of the Windows 2003 servers we had issues while performing a Volume Shadow Copy backup. If you have issues while performing a shadow copy backup usin…
Scenerio: You have a server running Server 2003 and have applied a retail pack of Terminal Server Licenses.  You want to change servers or your server has crashed and you need to reapply the Terminal Server Licenses. When you enter the 16-digit lic…
Look below the covers at a subform control , and the form that is inside it. Explore properties and see how easy it is to aggregate, get statistics, and synchronize results for your data. A Microsoft Access subform is used to show relevant calcul…
Is your OST file inaccessible, Need to transfer OST file from one computer to another? Want to convert OST file to PST? If the answer to any of the above question is yes, then look no further. With the help of Stellar OST to PST Converter, you can e…

810 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question