Question for upgrading

Binarus lists at
Tue Dec 18 06:03:58 EST 2018

On 13.12.2018 16:52, Egoitz Aurrekoetxea wrote:

> I was trying to upgrade part of our Cyrus imap installation, concretely
> that one consisting in still 2.3. I was planning to set up Cyrus 3.0. I
> have seen all works properly except for the unexpunge command because as
> someone stated here, a reconstruct -V max was needed.The problem is that
> this reconstruct command, takes ages and I'm not able to keep the
> service offline so many time.

Eventually you are meaning me by "someone", so I kick in here:

The reconstruct (for me) was only needed because I had transferred the
mailboxes using cyradm and the xfer command. As ellie has explained me
in detail, xfer is an IMAP extension which transfers the data on a lower
level than the standard IMAP commands.

Therefore, there is a trade-off: If you transfer the data at "low-level"
(e.g. xfer, file system), the transfer will be fast, and (at least in
case of xfer) everything (flags, permissions etc.) will be transferred
precisely, but you probably will have to reconstruct afterwards.

If you transfer the data at "higher" level, i.e. using standard imap
commands, for example using imapsync, the transfer will be slower, and
you eventually lose flags or permissions (note that I personally never
had any problem with imapsync, but can't say anything about other
software). But you don't need to reconstruct afterwards.

Could you eventually give us some figures?

In my case, I transferred between 10 and 20 GB of data from 2.4.16 to
2.5.10 (this is not that much data, but it contained a complicated
shared folder (public) namespace with thousands of deeply nested
folders). However, reconstruct -V max took less than 10 minutes afterwards.

Given that the source and the destination server were both running in
VMs on the *same* physical hardware which is over 7 years old and even
runs from normal HDD storage (it's a dual Xeon 5620 system, no SSDs),
this is very fast.

So I am curious what the size of your data is. You could do the transfer
and let the reconstruct run over the weekend when your users are not at
work. Based on my figures, you should be able to transfer and
reconstruct several TB of messages during one weekend ...



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