cyrus server and backup
I have never used the Cyrus IMAP server before and have just intalled it on a test system to evaluate it, with a view to moving our service over to it. We have over 20,000 users and need to upgrade our current system. One of our fundamental requirements is to be able to take security backups. These are primarily for recovery in case of hardware failures. The backups are conventional periodic full backups with intermediate incrementals. I am concerned that because Cyrus is a black box system which keeps track of its own internal organisation we may have problems if we restore a disc from our backups. It will take hours to do a backup and the files within the Cyrus structure will be changing as we do it. Are there going to be problems with inconsistencies between files? There is a secondary, but important use of our current backup service, which is to dig users out of a hole when they make mistakes: Occasionally a user will accidentally delete a message or even a whole folder and then come and ask if I can recover it for them. With our current backup system it is ussually very easy because I have no problem identifying the relevant files to be recovered. I seems to that it will be impossible to recover deleted messages because I will not be able to identify the files which I need. If I can identify the files, presumably there is no way to get them back into the Cyrus system? The only information I have been able to find which says anything about recovery is in the Server Overview and Concepts document. However, this does not go into sufficient detail and includes statements like Many objects in the configuration directory are discussed in the Database Recover section. I cannot find any section anywhere with a title of Database Recover! Any advice will be much appreciated. Phil. --- Phil Chambers ([EMAIL PROTECTED]) University of Exeter
Re: cyrus server and backup
On Fri, 04 Apr 2003, Phil Chambers wrote: I am concerned that because Cyrus is a black box system which keeps track of its own internal organisation we may have problems if we restore a disc from our backups. It will take hours to do a backup and the files within the Cyrus structure will be changing as we do it. Are there going to be problems with inconsistencies between files? There are two answers to this. The first is that doing snapshot backups should be possible on most plausible platforms, either by dropping a mirror off (requires mirroring, of course) or using fssnap (Sun) or LVM (Linux) to do a hot backup. The second is that in practice you can recover a mailbox by spinning on the files and then using reconstruct to rebuild the metadata. The worst you're going to do is break the unread flags and suchlike. There is a secondary, but important use of our current backup service, which is to dig users out of a hole when they make mistakes: Occasionally a user will accidentally delete a message or even a whole folder and then come and ask if I can recover it for them. We do that all the time. We pull the entire mailbox back, then grep for what the punter wants. With our current backup system it is ussually very easy because I have no problem identifying the relevant files to be recovered. I seems to that it will be impossible to recover deleted messages because I will not be able to identify the files which I need. If I can identify the files, presumably there is no way to get them back into the Cyrus system? If you can identify them by size or date, you just put them back into the mailbox and reconstruct it. ian
Re: cyrus server and backup
Phil Chambers wrote: I have never used the Cyrus IMAP server before and have just intalled it on a test system to evaluate it, with a view to moving our service over to it. We have over 20,000 users and need to upgrade our current system. One of our fundamental requirements is to be able to take security backups. These are primarily for recovery in case of hardware failures. The backups are conventional periodic full backups with intermediate incrementals. I am concerned that because Cyrus is a black box system which keeps track of its own internal organisation we may have problems if we restore a disc from our backups. It will take hours to do a backup and the files within the Cyrus structure will be changing as we do it. Are there going to be problems with inconsistencies between files? There is a secondary, but important use of our current backup service, which is to dig users out of a hole when they make mistakes: Occasionally a user will accidentally delete a message or even a whole folder and then come and ask if I can recover it for them. With our current backup system it is ussually very easy because I have no problem identifying the relevant files to be recovered. I seems to that it will be impossible to recover deleted messages because I will not be able to identify the files which I need. If I can identify the files, presumably there is no way to get them back into the Cyrus system? The only information I have been able to find which says anything about recovery is in the Server Overview and Concepts document. However, this does not go into sufficient detail and includes statements like Many objects in the configuration directory are discussed in the Database Recover section. I cannot find any section anywhere with a title of Database Recover! Any advice will be much appreciated. Search the list archives for detailed discussion of this topic. What we do is folder-level restores (we haven't had to restore more than one at a time yet -- the same approach works but it would be a lot of work), and we create a top-level folder that will be the restore target, restore the contents of the directory containing the user's folder that needs to be restored into the directory containing the restore folder, reconstruct that folder, and grant access to the user. It is up to the user to do whatever they want, presumably copying messages that were deleted accidentally. After one week, the restore folder is deleted. We decided to use a top-level folder rather than put it under each user to avoid quota issues (we could set a quotaroot on the restore subtree, but it is easier this way) and to make it easier to clean up expired restore folders. If this were a non-user error (we haven't had one of those), we would probably just restore the whole cyrus directory structure (depending on the damage) if reconstruct couldn't fix it. -- John A. Tamplin Unix System Administrator Emory University, School of Public Health +1 404/727-9931
