Migrating cyrus to zimbra open source with more 20 thounsands mailbox

[emacias]

Hi guys, we know that tool imapsync is for that, but actually mail server has more than 20 thounsands mailboxes in cyrus with quotas size around 300 Mb until 3 Gb.
this old production server can't be stopped because don't have redundancy and it's a critical and important service by the university where i work.
We made an estimation about migration time and the result is about 15 days of migration with old production server down.
Anybody have some other solution or experience about that?
Thanks!

[enjaurom]

I did that migration (cyrus to Zimbra) 2 years ago.I have less mailboxes (about 1000).
I use imapsync 2 times :

- 1 day before migration with cyrus server online ( big process, much time)
- The day of de migration with cyrus server offline ( only sync one day mail, little time )

Best regards

[Rich Graves]

Our 2000 large mailboxes took about 7 days for initial background sync. There was *no* general service downtime. The trick is to queue mail, kill existing sessions, and rename the account at the right time. Final incremental sync for the largest mailbox (5gb) took about 1 hour. I think I posted some scripts here about 30 months ago.

[emacias]

i' ll looking for stripts posted or if you have links, send it please. I also read this link maximizing imapsync speed - parallel runs
By Other Side, I received answer by other forum (linkedin) about subject. A group had a 1 month lead time on a recent upgrade project, they did for NYU and that was just an upgrade.... they had about 20K mboxes too. Migration is a lot more time consuming.

[raj]

why not do it in small steps of few thousand users at a time by using Split domain ( Split Domain - Zimbra :: Wiki ) setup of zimbra..you can take your sweet time and there will be 0 downtime

there IS planning and other stuff involved but no downtime for sure

Raj

[emacias]

Do you have experience using Zimbra with mailboxes around 20 thousands? Zimbra documentation on the Web shows their experience about that, but I want to know your experiencies because this migration is an important decision.

[raj]

Well we host way more than 20K mailboxes in total on our zimbra network for our customers.
we moved more than 30,000 mailboxes from Imail to Zimbra over the years.

what you need is a plan to move small set of users at a time and then you keep replicating that plan and you will finish with no downtime.
main highlights of the plan should be.

1) new zimbra infrastructure setup
2) full inventory of all user info and how to inform them about the changes that will take place.
3) make zimbra as you front end MX using split domain so all mail still flows to your old setup
4) move small set of uses at a time and update split domain info for them
5) repeat step 5 tilll you finish

i don't see any problem why you cannot do it.

PS: Most importantly question is which version you going to use OSS or NE..if you going to use NE..then zimbra will provide you ample support and planning.

if you doing OSS install then you need to sit and plan and do a small test setup. and as usual we are here to help.

Raj

[emacias]

We are going to use OSS. Well, We'll go to take your ideas for the migration. Split Domain is a good option, i will asking you if I have any doubt, Thanks for all!

[emacias]

Hi, i want to know your experience installing zimbra in virtual machines, Actually, we have SUN Blades, well now is Oracle Blade and other decition to take is to install zimbra in native S.O. from Blade or to install this in virtual machine. Of course performance, I/O and other elements are important to consider. Like you know, we have more of 20 k accounts and It's an importante service.

[raj]

well...if you going to use OSS which has no backup option without stopping the services then properly sized virtual environment can give you better "hot vm backup" options based on vendor.

zimbra works on Vmware like a charm, you just need to now your Virtualization stuff.

Raj