Re: Restart from....? (DRP)

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Hi,

Quoting Albert Shih <Albert.Shih@xxxxxxxx>:

Hi everyone

I've a question about DRP (Disaster Recovery Plan), what's the easiest (=
fastest) way to rebuild a server (with the data) after a server « disappear » (fire,
water flood, etc.).

I see three way to « backup »  the data :

  Replication,

  Backup service (inside cyrusimapd 3),

  Filesystem backup (whatever the technic)

For replication my concern is the speed of the replication, the main server
(I got only one server) got lots of RAM, got SSD, and SAS disk, the
replication got SATA disks (lots of RAM too). When I check I think
everything are indeed replicated on the « slave » but with some delays
(1/2 days).


We have distributed our users across 6 (virtual) servers in an cyrus 2.4 murder setup. The servers are grouped in pairs, so that one is running on hardware in one building and the other in the other. On each server there are 3 cyrus instances running, one frontend, and one backend and one replic.

In case of disaster, or planed maintenance we will start the replic as normal backend (we use service ip addresses for each backend and move this ip to the other server so we don't have to update the
mupdate master mailbox.db.


The rolling replication is able to keep up. So normally there is only a small delay (2-5 Secs). If there is a traffic peak (many newsletters) it may take up to 1-2h. I have only seen longer delays in case of a corrupt mailbox where the replication bailed out. We are monitoring the size of the replication log.

We have ~ 41000 Accounts ~13.5 TB Mails, The VMs are running in an RHEV System. Each Server has 20 GB Ram, 8 CPU-Cores, the Mails are stored on EUROstor iSCSI Systems with SATA disks Recently we migrated the metadata onto a new EUROstor iSCSI System with SSDs. At the moment we plan to migrate to Cyrus 3.0 to use archive partitions so that the recent mails will be stored on a iSCSI System with SAS disks,
and the older mails will be moved to the old iSCSI system with SATA disks

In addition to the disaster recovery plan we use "expunge_mode: delayed" and "delete_mode: delayed" and normal file based backup for the "I deleted my very importent mail by accident" use case.


Regards

   Michael Menge


--------------------------------------------------------------------------------
M.Menge                                Tel.: (49) 7071/29-70316
Universität Tübingen                   Fax.: (49) 7071/29-5912
Zentrum für Datenverarbeitung mail: michael.menge@xxxxxxxxxxxxxxxxxxxx
Wächterstraße 76
72074 Tübingen

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