[MlMt] MailMate and Time Machine

[Glenn Parker]

On 22 Oct 2020, at 10:07, Steven M. Bellovin wrote:

> That's not the issue. I've excluded Database.noindex for
> years—it's very large, and because MailMate doesn't try
> to synchronize writes to it with changes to messages, it's
> not likely to be correct after a restore in any event. Let me
> restate the problem.
>
> It is *not* just the number of messages. As I noted, on a machine
> with the same number of messages, backups do not take unduly
> long. Files that are not changed are not backed up anew, though
> a new hard link is created to them, and that of course takes
> time. Fine; I can deal with that. Something more is going on.
> On my main account, I have 147 top-level mailboxes. *12* of
> them have been changed this year, though there are a few where
> there are sub-mailboxes. The change in time for backups is
> quite disproportionate to the number of mailboxes changed.
> There's something more that Time Machine is doing, and I don't
> know what.

I suppose there are a lot of possible reasons why Time Machine could run 
into performance issues, and figuring that out will require some general 
sleuthing and probing of your system. It’s interesting that you have 
two systems with different behaviors, so I would start by looking at 
what distinguishes them.

Are there differences in the backup media? Operating systems? File 
systems of the source and target? Networks (wifi vs. ethernet)?

Is the backup device being used for other functions while backups are 
running?

Are you running other tasks on the machine that leave no idle time for 
Time Machine to do its work?

Do you have anti-virus software running anywhere? (Don’t let it 
operate on Time Machine backups.)

Would it be feasible to get some clean backup media and just try a fresh 
Time Machine backup?

Also, it might be worth exploring exactly what files are being backed up 
with a utility like BackupLoupe. For me, the size of the data in need of 
backing up has always been the limiting factor. If it turns out that 
you’re backing up more files than you thought, that would be an 
important avenue to explore.

Finally, check your Console app to see if there are other problems 
slowing down the system.

Glenn P. Parker
glenn.parker at comcast.net
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