Re: [foxboro] Convert a Foxboro P91 Server from a P91 Dell Power Edge 2800 to a new Dell Power Edge 2900
- From: "tjvandew@xxxxxxxxx" <tjvandew@xxxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Tue, 24 Feb 2009 05:41:00 -1000
Corey,
Good question. Scheduling the backup during times when applications
are not in use would be a good thing. In the case of the Aim historian,
it is always collecting data but this whole backup and restore scheme
assumes that you are willing to take a loss of historical data because
it is highly unlikely that you will have performed an online backup
immediately before you lose a hard drive and have to restore. The other
more significant issue is that new blocks or compounds get added between
the last online backup and your need to restore. This means you will
have CSA and workfile mis-matches that you will have to resolve. From
what I can see there is no silver bullet that addresses all of these
issues. So you go with the option that will hopefully get you back up
and running with the least pain.
As I said before, we did have one instance where the boot record on
a P92 was corrupt and we couldn't boot off the hard drive but we were
able to boot off of the Acronis "True Image" CD and backup the D:
partition. We built a new box from a Day 0 and then restored the D:
partition and we were back up and running on the same day. It was a
risk but we were successful. "I'd rather be lucky than good";<)
Tom VandeWater
Control Conversions, Inc.
Corey R Clingo wrote:
> I'm curious -- with any of these solutions, is there any concern about
> consistency of the backups when doing them online? I see 2 potential
> issues:
>
> 1. Single-file inconsistency -- files being backed up while being written,
> leaving the backup copy corrupt. Windows has Volume Shadow Copy for this,
> but I believe applications have to be written to take advantage of it (and
> I'm guessing most of Foxboro's aren't).
>
>
> 2. Multiple-file inconsistency -- one file not "matching" another file
> because they were backed up at different times while an application using
> both of them was writing to them.
>
>
> The scary thing about this to me is that it may only bite you 1 time in
> 100. It must still be an issue for some, as some (large) applications we
> use that are constantly writing data to disk have "write pause" or
> buffering options to allow you to run backups on consistent file sets.
>
>
> Corey Clingo
> BASF Corp.
>
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