You're equating dead server and completely erased drives, which is an
erroneous assumption on your part.

There are two "full system crash" scenarios in which I could see not being
able to recover from the logs.

First - drive controller failure that includes destroying BOTH the database
and log volumes (you DO have them on different RAID sets, right?????). This
is only an issue if you have 1 and only 1 RAID channel/array.

Second - datacenter fire that physically destroys the box. You're DOA, even
in your scenario, because the tape sitting in the drive with your most
recent differential is melted, along with the server it backed up.

As long as you have 2 of the 3 following items, you're 100% fine:
-intact Database volume
-intact log volume
-intact copy of the last full Exchange aware backup

With any 2 of those 3, you can recover your system to precrash considition
with no committed data lost.

Differentials are a waste of time for Exchange in 99% of all cases.
SQL-esque databases are a different story, but that's another forum entirely

Roger
------------------------------------------------------
Roger D. Seielstad - MCSE
Senior Systems Administrator
Peregrine Systems
Atlanta, GA
http://www.peregrine.com


> -----Original Message-----
> From: Michel, David [mailto:[EMAIL PROTECTED]] 
> Sent: Monday, January 07, 2002 1:40 PM
> To: Exchange Discussions
> Subject: RE: Win2k backup and Exchange
> 
> 
> As much as I appreciate multiple links and sarcastic 
> comments, I do not see anywhere in the whitepaper from either 
> 5.5 or 2000 on how you can roll logs forward IF THE LOGS 
> AREN'T THERE...  Have you ever heard of a full system crash?  
> Although I admit it is much less likely than any other type 
> of failure it is still possible to lose the entire server, 
> isn't it?  And if it is, the logs you are so fond of 
> referring to will be about as useful as your sarcasm.  If you 
> ever have the misfortune to work for lawyers you will find 
> that there are certain things you do and deal with and a full 
> system daily backup which is as up-to-date as possible is an 
> absolute requirement.  That is the reason that I am asking 
> and why I feel my use of differentials is "warranted".  If I 
> am not mistaken, a tape of any sort is only going to be as 
> useful as the last information written to it if that is the 
> only source of data, is it not?  Therefore, a full server 
> crash in the late afternoon with only last night's full 
> backup leaves you SOL for almost a full day's work.
> 
> However, if I am incorrect in my assumption that a tape which 
> contains a full backup along with differential backups will 
> allow me to rebuild my server completely and restore it to 
> the point of the last differential then I would honestly be 
> interested in hearing why. Furthermore, if there is a way to 
> restore and roll the logs should the server that the logs 
> were on be completely dead using just a full backup from the 
> night before than I retract all sarcasm on my part and look 
> forward to hearing how that process would work. 
> 
> 
> -----Original Message-----
> From: Kevin Miller [mailto:[EMAIL PROTECTED]]
> Sent: Monday, January 07, 2002 12:36 PM
> To: Exchange Discussions
> Subject: RE: Win2k backup and Exchange
> 
> 
> READ IT. Learn it. Love it. Tell it nice things. Sleep with 
> it under you pillow
> 
> 5.5 DR white paper 
> http://www.microsoft.com/Exchange/techinfo/administration/55/B
> ackupResto
> re.asp
> 
> 2k DR white paper 
> http://www.microsoft.com/Exchange/techinfo/deployment/2000/e2k
> recovery.a
> sp
> --Kevinm M, WLKMMAS, UCC+WCA, And Beyond
> Drive thru Admin, Would you like Fries with that?
> 
> 
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]] On Behalf Of Don Ely
> Sent: Monday, January 07, 2002 9:26 AM
> To: Exchange Discussions
> Subject: RE: Win2k backup and Exchange
> 
> 
> You've never heard of database logging have you?  In the 
> event of a restore, when the IS is restored and the 
> transaction logs are replayed, you have lost nothing.  You 
> can restore right up to the point of failure.  Therefore your 
> use of Differentials is unwarranted....
> 
> D
> 
> -----Original Message-----
> From: Michel, David [mailto:[EMAIL PROTECTED]] 
> Sent: Monday, January 07, 2002 9:27 AM
> To: Exchange Discussions
> Subject: RE: Win2k backup and Exchange
> 
> 
> I have read it and I want to reiterate that I do plan on 
> doing a nightly full backup. However, since the Exchange 
> server has it's own tape backup system, I would also like to 
> do differentials in addition to the full. Therefore, should a 
> complete crash happen I'm backed up to within an hour or so 
> of crash time rather than the previous night.
> 
> -----Original Message-----
> From: McGilligan, Sean [mailto:[EMAIL PROTECTED]]
> Sent: Monday, January 07, 2002 12:09 PM
> To: Exchange Discussions
> Subject: RE: Win2k backup and Exchange
> 
> 
> David,
> 
> First,I would read the paper disaster recovery.
> Second,I would ask the question why can you not do full 
> (normal) backups every day unless of course your data 
> outstrips your tape size on each server. I think you are 
> reading into differentials too deeply. Personally I would 
> recommend Veritas Backupexec as NTBackup is a stripped down 
> version albeit free, but again it comes down to the horses 
> for courses and each person can tell a different story where 
> backups are concerned. My reasoning is the restore times from 
> testing are faster with Veritas. Whether you want to pay that 
> much more is the question?.
> 
> Yours sincerely,
> Sean McGilligan
> 
> 
> 
> 
> 
> [
> I realize there are no stupid questions but only stupid 
> people who ask questions so I'll throw my hat into the stupid 
> ring as this is probably very simple...
> 
> I finally got my boss to buy a DLT drive exclusively for each 
> of my Exchange 2000 servers.  From all I've read here and 
> elsewhere I decided to use NTBackup rather than ARCServe on 
> my servers.  I cannot, however, find a way to setup the 
> backups correctly.  I aim to do a nightly full backup at 11pm 
> with differentials every two hours from 6am until 8pm when 
> the tape would be replaced for that night's backup.  I see in 
> the backup wizard how to set the daily backup as a "normal" 
> and how to schedule a second "differential" backup for only 
> the information store at my selected times.  However, the 
> option to "append" rather than overwrite the media is grayed 
> out on the differential.  If this differential is going to 
> overwrite the full backup then a single tape source for 
> backup isn't feasible.  I'm sure it is but I'm just missing 
> something so anything you can offer would be appreciated. ]
> 
> 
> 
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