NetBackup Granular Recovery Technology – Tips and Caveats
The granular backup and recovery technology (GRT), firstly introduced at 6.5.3 is a really awesome feature of NetBackup which allows users to recover their stuff on message or document basis, not a whole mailbox or an information store. With this new technology we can provide more services to our customers, who are looking not only for fast backups, but also for fast, business-oriented recovery process. However, this technology does its job using more resources than you can expect from the first look and not as fast as it sounds in the announcement letters.
I am techical consultant for those Symantec products which were VERITAS-branded and recently I have completed couple of projects with extensive usage of GRT technology (mostly for the Exchange databases), and here you find some tips and tricks as well as links to the documentation and some points which are really missing from the documentation. NetBackup is only player in the enterprise backup game who can provide both huge compatibility list and broad set of contemporary backup technologies (and actually inventing new ones). This is really financial advantage comparing to the competitor's products which require swapping of hardware in some cases or even point you which hardware vendor you have to choose for the best backup performance.
The very first step you need to do is to read the documentation carefully. The GRT is really handy thing but it requires a disk type of storage unit for recovery and this quite restrictive (comparing to MS DPM) limitation is usually excluded from the commercials. But as pre-sales/post-sales person or sysadmin you must keep it in mind. As per 6.5.4 the only supported types are: Basic Disk, Advanced Disk and Pure Disk, all others (including OpenStorage) are not supported. The most frequent question I hear from my customers is: “Can we perform a backup to disk, duplicate it to a tape and recover from it?” – the correct answer is “Yes, you can duplicate it to the tape and even recover from it, but not granular items. In order to be able to recover granular items, duplicate it back”. Once you got a disk storage unit, go and read this article: How to configure and use Exchange Granular Restore in NetBackup 6.5.3 http://seer.entsupport.symantec.com/docs/316982.htm.
That guide is good; however, I found some steps are missing there. Indeed, you need to follow another article (quite old one!) and make sure that you can browse mailboxes, prior to start playing with the GRT: DOCUMENTATION: How to configure NetBackup for Mailbox backups of an Exchange 2000/2003 server http://seer.entsupport.symantec.com/docs/245184.htm. Pay attention to the account and its permissions at the Exchange server and do not forget to set the service mailbox variable in the client properties.
Try to browse the mailbox list; it should look like at the picture below:
If it’s shows you the mailbox list, you are ready for the next step. Bear in mind, that most critical step there is to set up an NFS server properly as it written in the guide. Create a regular Exchange backup policy and put Microsoft Information Store:\* or Microsoft Information Store:\First Storage Group\ at the Backup Selections tab and do not forget to tick this checkbox:
Basically that’s it. You can now perform the backup of the information store and recover granular items from it. Do not forget about the limitations (as I said above, some of them are quite restrictive):
- Instant recovery is not supported with individual item restores;
- Compression and Encryption are not available for document-level restores.
- While incremental schedules can be added to a policy when the Enable document restore option is enabled, individual item restore cannot be performed from this type of backup.
- When selecting Enable document restore in the policy, you must add only the Microsoft Information Store, storage groups, or databases to the Backup Selections list.
- This feature only supports Full and user-directed backups. NetBackup allows creation of a complete policy for disaster recovery, with all the various types of schedules. However, an incremental schedule produces a backup image that can only be used for database recovery.
- Backups must be made to a disk storage unit, not to tape, and individual item restores must be made from a disk storage unit. Backups can be manually duplicated to tape, but cannot be restored from the tape copy.
- You must configure NetBackup for browsing and restores of individual mailboxes and public folders. See "Configuring NetBackup for backups and restores of individual mailboxes and public folders" in the NetBackup for Microsoft Exchange Server Administrator's Guide.
- In the Host Properties for a server, the General Server tab contains the option "Document-level restore options". This functionality is not available for Exchange backup images.
- Exchange Server provides a feature to retain deleted items for a period of time after an item is “permanently" deleted. Because the deleted items still exist, NetBackup includes them in the backup image. NetBackup displays these items when browsing the granular backup image and these items can be restored
Huge list, isn’t it?
That’s great but the actual problem comes after couple of successful backups and usually sounds like “why we cannot use this technology with incremental backups”. And here we are facing real world’s problem – your disk storage is limited and you cannot use your latest and greatest deduplication OpenStorage device to reduce the space consumption. Obvious decision is to duplicate some old images to the tape and leave some most recent on the disk. This can be achieved by leveraging the new Storage Lifecycle Polcies feature (requires Advanced Disk license). It works very well and really saves space, but unfortunately in the 6.5.3 edition you can’t control the indexing process which starts at the time of such duplication and my good advice is to go for 6.5.4 version. It is a known bug and 6.5.4 contains workaround using the GRANULAR_DUP_RECURSION registry key/bp.conf entry. Have a look into this article: BUG REPORT: Duplication of Exchange backup with Granular Restore information from disk to tape is very slow. The job appears to have hung http://seer.entsupport.symantec.com/docs/317302.htm Actual bug is really annoying:
Duplication (via Manual or SLP or DSSU) of Exchange backup with Granular information will take extra time when duplicate from Disk to Tape. The extra time is required by NetBackup to catalog the Granular Exchange information. Behavior: Duplication of Exchange with Granular information will take extra amount of time to complete. The duplication job itself does not show any progress and may appear hanging. And here is an explanation: When backup data is on disk and users need to review the Granular information, NetBackup will mount the database on disk and display the data.
When backup data is on tape, users won't be able to perform an Individual item restore; however, they still can view the individual items from the Backup, Archive and Restore GUI. In order for this information to become available, NetBackup has to collect it when starting the duplication (or tape backup) process.
Huh! Very good reason for the upgrade!
As a wrap up I’d like to recommend this way of image rotation until Symantec will release version which will be able to recover granular items from the incremental backup. First – classify your data. Maybe some of your storage groups don’t need the GRT technology for their backups and regular mailbox-level backups are sufficient for them. Second – keep your setup simple. If you really want to move some old images to the tape storage in order to conserve space at the disk storage unit, consider to invest in the Storage Lifecycle Policies feature rather than writing complex scripts. Third – avoid duplicate backups. This technology is designed to provide you an ability to get granular recovery as well as disaster recovery image by single backup pass (and main reason why we are recommending NetBackup for this task), but some customers still think they need to do a separate backup of the information store to the tape, and this step is redundant.