Questions on Migration
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Thread: Questions on Migration

  1. #1
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    Questions on Migration

    Hello All,

    I'm a long-time ZCS Open Source admin / user. In fact, I've been a moderator on the Zimbra forums since nearly the beginning, although I must admit I've been pretty inactive for quite awhile. Anyway, I used to keep fairly current with new Zimbra releases, but for various reasons I haven't done any Zimbra or OS upgrades on my server for quite some time. I am currently running ZCS 7.2.2 FOSS version on a CentOS 5.4 system. I'm considering upgrading and since RHEL / CentOS 5.x is getting old and no longer supported for ZCS I would like to move to a new server running a more current OS. I think the ZeXtras Migration Tool may be very helpful for this, but I have several questions:

    1) As I said, my current Zimbra system is running CentOS 5.4 (64-bit). Will there be any issues running the Migration Tool on this OS? I don't see CentOS 5 on the Compatibility List, although this seems to be more for the import than the export.

    2) Are there any plans to support ZCS 8.5 and/or RHEL / CentOS 7.x?

    3) My goal would be for the new server to have the same host-name and IP address of the existing server. Basically replacing the current server with the new server, and from the user standpoint nothing really changes (except new version of Zimbra). What are the recommendations for preparing the new server for this type of migration? Do I install ZCS and set it up with a temporary / dummy domain?

    4) If I'm reading correctly, I need enough disk space to backup my current Zimbra environment and restore the info on the new server. So essentially I will need twice as much free disk space as my current installation. Is it basically a 1:1 relationship for current space used to backed up data to restored data?

    5) I know there are a lot of factors that come into play, but is there any way to guesstimate the amount of time the migration will take? I'm running in a VMware 5.1 environment. The current server is a VM and the new server will be a VM as well. We currently have around 345 GB of Zimbra data. Ideally I would hope to present a new disk to the current server for the export and then take it away and present it to the new server for the import. So, no copying over the network would be involved. I've briefly looked at the Incremental Migration process, but would like to keep things as simple as possible. Since all our external email comes into an email anti-spam / anti-virus gateway first, I can schedule some off-hours downtime without fear of losing any email.

    I may not do this migration for quite some time, but never too early to start preparing. If there are any other things I should consider, beyond what I've listed here, any info, tips, pointers, etc. would be greatly appreciated.

    Thanks in advance,
    John

  2. #2
    ZeXtras Community Manager ZeXtras Employee Cine's Avatar
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    Hello John,
    welcome to the forums!

    Quote Originally Posted by soxfan View Post
    1) As I said, my current Zimbra system is running CentOS 5.4 (64-bit). Will there be any issues running the Migration Tool on this OS? I don't see CentOS 5 on the Compatibility List, although this seems to be more for the import than the export.
    The only platforms officially supported by ZeXtras Suite are those officially supported by Zimbra, but since Zimbra works fine on CentOS 5 it won't be a problem to use ZeXtras Suite/ZxMig for your migration!

    Quote Originally Posted by soxfan View Post
    2) Are there any plans to support ZCS 8.5 and/or RHEL / CentOS 7.x?
    Sure! You can find the official announcement about Zimbra 8.5.0 compatibility HERE, while RHEL/CentOs 7.x will be added to the compatibility list as soon as a stable ZeXtras Suite release compatible with Zimbra 8.5.0 is released...

    Quote Originally Posted by soxfan View Post
    3) My goal would be for the new server to have the same host-name and IP address of the existing server. Basically replacing the current server with the new server, and from the user standpoint nothing really changes (except new version of Zimbra). What are the recommendations for preparing the new server for this type of migration? Do I install ZCS and set it up with a temporary / dummy domain?
    The answer to this question depends on whether you wish to keep the same LAN IP or if you are willing to change it: in the first case, things may get a little clunky due to the need of "switching" IP addresses during the migration, while if you are willing to change it it's as easy as setting up a new server - your DNS will keep resolving the old server's hostname(s) with its IP and your firewalling rules will forward traffic to the appropriate server regardless of the hostname so no need for dummy domains...

    Quote Originally Posted by soxfan View Post
    4) If I'm reading correctly, I need enough disk space to backup my current Zimbra environment and restore the info on the new server. So essentially I will need twice as much free disk space as my current installation. Is it basically a 1:1 relationship for current space used to backed up data to restored data?
    A 1:1 relationship is the worse case scenario - 1:0.7 is a more realistic ratio as exported data is deduplicated and compressed...

    Quote Originally Posted by soxfan View Post
    5) I know there are a lot of factors that come into play, but is there any way to guesstimate the amount of time the migration will take? I'm running in a VMware 5.1 environment. The current server is a VM and the new server will be a VM as well. We currently have around 345 GB of Zimbra data. Ideally I would hope to present a new disk to the current server for the export and then take it away and present it to the new server for the import. So, no copying over the network would be involved. I've briefly looked at the Incremental Migration process, but would like to keep things as simple as possible. Since all our external email comes into an email anti-spam / anti-virus gateway first, I can schedule some off-hours downtime without fear of losing any email.
    Unfortunately, there are too many factors involved in order to make an estimate - my suggestion would be to run a mock-up test in order to evaluate your infrastructure's migration performances and plan accordingly.

    Quote Originally Posted by soxfan View Post
    I may not do this migration for quite some time, but never too early to start preparing. If there are any other things I should consider, beyond what I've listed here, any info, tips, pointers, etc. would be greatly appreciated.
    Some pointers in no particular order:
    - Check your source server's health before starting with the migration: this includes file permissions, DB/BLOB health, filesystem integrity...
    - Run some tests until you feel comfortable enough to migrate.
    - The Incremental Migration is more flexible, give it a thought.
    - If you need more time for your tests, get in touch with us! We'll be glad to provide you with an Extended Trial License...
    - If your users are running a POP3 client, make sure the "Delete messages from the server" option is enabled to avoid item duplication.

    Quote Originally Posted by soxfan View Post
    Thanks in advance,
    John
    You're welcome! Feel free to post any question or doubt that might arise before or during your migration

  3. #3
    ZeXtras Community Manager ZeXtras Employee Cine's Avatar
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    Quote Originally Posted by Cine View Post
    A 1:1 relationship is the worse case scenario - 1:0.7 is a more realistic ratio as exported data is deduplicated and compressed...
    Sorry, I completely misinterpreted the question...

    The 1:0.7 ratio is referred to the current-to-backup sizing, while the space required on the destination server is much likely be higher - as Zimbra's deduplication during the migration will probably never kick in due its cache-based engine.
    After the migration, however, you can run a full volume deduplication with ZeXtras Powerstore to reduce the used space and make it lower than the original server's.

    Also, an addendum to my answer to Question 3: make sure that the new server is properly configured to resolve its hostname with its own IP, otherwise Zimbra and ZeXtras CLI commands might end up being sent to the original server.

    Have a nice day,
    Cine

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    Cine,

    Thank you so much for your prompt, extensive, and informative answers to my questions. I really appreciate it.

    First off, I want to apologize for posting question 2 concerning ZCS 8.5 / CentOS 7. I really did do some searching around prior to posting my questions, but somehow totally missed your official announcement.

    I am definitely going to look into the Incremental Migration some more. I had hoped to do one, straight, clean migration from the current system to the new system, but just with the amount of data that will be moving around it probably makes more sense to do things incrementally.

    I'm still stuck on my question 3 and your response. As far as the host-name and IP address, I really think I'm going to keep the same. I know I did this on a previous upgrade / move of Zimbra to a new server. I'm pretty confident I can figure this out and will make the changes after the migration is complete. This is beyond the scope of my questions concerning ZeXtras. What I'm a bit confused on though is installing and configuring Zimbra on the new server prior to migration. Let's say as an example, my current Zimbra domain is "mydomain.com". When I install Zimbra on the new server it is going to make me configure a domain. Do I keep it as "mydomain.com"? When I do the import using ZeXtras Data Import is it going to wipe out any settings I've put in on the new server for "mydomain.com" and replace it with my current server "mydomain.com" settings? (This would be what I would want.)

    Thanks again, and I look forward to trying things out.
    John

  5. #5
    ZeXtras Community Manager ZeXtras Employee Cine's Avatar
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    Hello John!

    Quote Originally Posted by soxfan View Post
    Cine,

    Thank you so much for your prompt, extensive, and informative answers to my questions. I really appreciate it.
    You're welcome!

    Quote Originally Posted by soxfan View Post
    First off, I want to apologize for posting question 2 concerning ZCS 8.5 / CentOS 7. I really did do some searching around prior to posting my questions, but somehow totally missed your official announcement.
    No problem at all

    Quote Originally Posted by soxfan View Post
    I am definitely going to look into the Incremental Migration some more. I had hoped to do one, straight, clean migration from the current system to the new system, but just with the amount of data that will be moving around it probably makes more sense to do things incrementally.
    You can do a straight migration aswell, but using ZeXtras Backup on both servers will make it easier to face any setback that might happen during the migration (that's why I personally prefer it over ZxMig+ZxBackup)... All in all, however, it's your choice so feel free to go the way you feel more comfortable with.

    Quote Originally Posted by soxfan View Post
    I'm still stuck on my question 3 and your response. As far as the host-name and IP address, I really think I'm going to keep the same. I know I did this on a previous upgrade / move of Zimbra to a new server. I'm pretty confident I can figure this out and will make the changes after the migration is complete. This is beyond the scope of my questions concerning ZeXtras. What I'm a bit confused on though is installing and configuring Zimbra on the new server prior to migration. Let's say as an example, my current Zimbra domain is "mydomain.com". When I install Zimbra on the new server it is going to make me configure a domain. Do I keep it as "mydomain.com"? When I do the import using ZeXtras Data Import is it going to wipe out any settings I've put in on the new server for "mydomain.com" and replace it with my current server "mydomain.com" settings? (This would be what I would want.)
    It seems that Question 4 was not the only one I misinterpreted
    While ZeXtras Backup overwrites any domain setting during an import, my suggestion would be to use the fqdn as the "first" mail domain as prompted by the installer so that system resource accounts will be created on a dedicated, clean domain and won't be in the way during the migration...

    Quote Originally Posted by soxfan View Post
    Thanks again, and I look forward to trying things out.
    John
    You're welcome, have a nice day!

  6. #6
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    Thanks again Cine! We're on the same page now on my question 3. That was my thought as well, to create the default FQDN domain during setup; what I referred to as the "dummy / temporary" domain. I probably should have worded it better.

    It will probably be awhile before I attempt anything, but at least now I have a starting point for a game-plan moving forward.

    John

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