TECHALERT: A potential for data loss exists when using NetBackup 6.5.x PDDO with PureDisk 6.6.1.1 or PureDisk 6.6.0.3. This issue specficially affects Optimized Duplication.

Article:TECH153440  |  Created: 2011-02-15  |  Updated: 2011-02-22  |  Article URL http://www.symantec.com/docs/TECH153440
Article Type
Technical Solution


Issue



TECHALERT:  A potential for data loss exists when using NetBackup 6.5.x PDDO with PureDisk 6.6.1.1 or PureDisk 6.6.0.3.  This issue specficially affects Optimized Duplication. 


Cause



 

 


Solution



Introduction:

A potential for data loss has been discovered when performing Optimized Duplication of backup images that are 700GB or greater with the default fragment size (50GB), or if CheckPoint Restart is in use.   Backup images in this range will duplicate with a status 0 (successful) but cannot be restored.  

 

What is affected:

The following products are affected by this, on all supported operating systems. 

- NetBackup 6.5.x using PDDO with the following PureDisk versions

PureDisk 6.6.0.3 with EEB20 provided by support (also known as ETrack 2127746 or Rocksolid binaries)

PureDisk 6.6.1.1

 

How to determine if affected:

Scenario A: There is a potential for data loss if ALL of the following conditions have been met:

- One of the products above is being run on a supported operating system

- Optimized Duplication is in use to create backup copies.

- Checkpoint Restart is enabled

- All copies of the backup (that weren’t duplicated with optimized duplication) expire or are scheduled to expire.

 

Scenario B: There is further potential for data loss if ALL of the following conditions have been met:

- One of the products above is being run on a supported operating system

- * A backup exceeds 700gb in size, using the Default fragment size (50GB)

- Optimized Duplication is used to duplicate that backup

- All copies of the backup (that weren’t duplicated with optimized duplication) expire or are scheduled to expire

 

* If the default fragment size is changed to be a lower value, then there is a potential for data loss for backups of a lesser size.

Data can only be lost if the source copy is expired and only affected optimized duplication copies remain.   This becomes especially critical if the Source copy is set for a shorter retention (such as 30 days) than the Optimized Duplication copy.  If the only remaining copies meet the above criteria when the Source expires, then data will be lost.

If affected images may exist based on the criteria above, please verify images based on Step 1 of the preventative workaround, below.

 

Preventative Workaround

If a duplication has completed with a Status 0 but is not restorable due to this issue, perform the following:

1. Use bpverify or the NBU console to verify all non-COPY1 images on PureDisk storage units.

One method of achieving this is to run the following command against any disk pool that is a target for optimized duplication, to verify its images

bpverify -stype PureDisk -dp <DISKPOOL> -s mm/dd/yyyy HH:MM:SS

 

2.   If an image is affected and a lower copy number (e.g.: COPY1) still exists:

- Expire the affected image copy

- Duplicate it again to the target Storage Unit without optimized duplication (use "bpduplicate" or the NBU console)

 

Emergency Engineering Binaries are available to prevent this issue from occurring.  If potentially affect, contact support and reference Etrack 2273601 (for 6.6.0.3) and Etrack 2275134 (for 6.6.1.1)

 

Formal Resolution

The formal resolution to this issue (Etrack 2273601) will be included in the following release:

- PureDisk 6.6.1.2

If an EEB or Formal Resolution is applied, it is still important to ensure that no copies created prior to applying the fix are affected.

Please check back with this article, as it will be republished with any updates.

 

 

Best Practices:

Symantec strongly recommends the following best practices:

1. Always perform a full DR backup prior to making any changes to your environment.

2. Always make sure that your environment is running the latest version and patch level.

3. Perform periodic "test" restores.

4. Subscribe to technical articles.

 

How to Subscribe to Email Notification:

Directly to this Article: 

Subscribe to this article by clicking on the Subscribe via email link on this page to receive notification when this article is updated with Release Information.

 

Software Alerts:

If you have not received this TechNote from the Symantec Email Notification Service as a Software Alert, you may subscribe via email and/or RSS using the links provided at the following pages:

 

NetBackup Alerts

http://www.symantec.com/business/support/index?page=content&key=15143&channel=ALERTS

 

PureDisk Alerts

http://www.symantec.com/business/support/index?page=content&key=52672&channel=ALERTS

 




Article URL http://www.symantec.com/docs/TECH153440


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