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zmdedupe

Posted: Thu Oct 12, 2017 3:03 pm
by aiko
Hello,

has anybody of you tried zmdedupe? Or does somebody run it regularly?
Is it safe? Or have tears been shed later?

Kind regards,
Aiko

Re: zmdedupe

Posted: Thu Oct 12, 2017 3:33 pm
by phoenix
Why do you think it necessary to run it on any sort of basis? If you want to see who's used it the put the word into the search bar, top right, and read what people say about it or you could always do an internet search for a few different results. ;)

Re: zmdedupe

Posted: Fri Oct 13, 2017 10:26 am
by aiko
Hello Phoenix,

I searched the internet of course and the results were sobering.

In 2014, somebody mentioned, that it doesn't work for secondary volumes:
https://bugzilla.zimbra.com/show_bug.cgi?id=87915
(We don't have secondary volumes anymore luckily.)

In 2015, somebody asked for some documention:
https://bugzilla.zimbra.com/show_bug.cgi?id=102069
(Yeah. And that's it. Story ends here.)

I would like to ask some of our users to put ~100GB of mails back on the Zimbra server. Those mails are currently on a different IMAP server. And I guess, that I actually do not need additional 100GB of disk storage because of zmdedupe. Those mails were originally stored on the Zimbra server and I expect, that somebody still has them in his/her mailbox as a copy. Our server contains 1.6TB of mails at the moment.

But is it possible to let zmdedupe run at any time? Does it hit performance hard? Stay all mailboxes online during that time? I could not find an answer.

Different story: I needed zmrestore once and immediately triggered two bugs, that were at least documented in Bugzilla. That is why I am asking. Does anybody use zmdedupe regularly or is it some forgotten tool that may or not may eat all our emails? :)

Kind regards,
Aiko

Re: zmdedupe

Posted: Fri Oct 13, 2017 11:42 am
by L. Mark Stone
aiko wrote:Hello Phoenix,

I searched the internet of course and the results were sobering.

In 2014, somebody mentioned, that it doesn't work for secondary volumes:
https://bugzilla.zimbra.com/show_bug.cgi?id=87915
(We don't have secondary volumes anymore luckily.)

In 2015, somebody asked for some documention:
https://bugzilla.zimbra.com/show_bug.cgi?id=102069
(Yeah. And that's it. Story ends here.)

I would like to ask some of our users to put ~100GB of mails back on the Zimbra server. Those mails are currently on a different IMAP server. And I guess, that I actually do not need additional 100GB of disk storage because of zmdedupe. Those mails were originally stored on the Zimbra server and I expect, that somebody still has them in his/her mailbox as a copy. Our server contains 1.6TB of mails at the moment.

But is it possible to let zmdedupe run at any time? Does it hit performance hard? Stay all mailboxes online during that time? I could not find an answer.

Different story: I needed zmrestore once and immediately triggered two bugs, that were at least documented in Bugzilla. That is why I am asking. Does anybody use zmdedupe regularly or is it some forgotten tool that may or not may eat all our emails? :)

Kind regards,
Aiko
We use zmdedupe frequently on 8.6 and above with no tears.

It is very useful when you have a multi-server Zimbra installation and are moving mailboxes across mailbox servers, and after restoring a mailbox you intend to keep.

Keep in mind however that it won't find everything that can be deduped; to my understanding it uses a cache of a few thousand items.

We learned this the hard way when we were doing a Zimbra upgrade. We upgraded the LDAP, MTA and Proxy hosts in place, but to avoid downtime for the users, we built new mailbox servers and just moved mailboxes from the old mailbox servers to the new mailbox servers. There were about 1K mailboxes on each mailbox server. After the moves were done, we ran zmdedupe, but found we were still using about 20% more storage on the new servers than on the old. After that, we started running zmdedupe after every 100 or so mailbox moves and got slightly better results.

The functionality within the Zextras Suite (coming in Zimbra 8.8) is better I'm told.

Hope that helps,
Mark