BUG REPORT: Incremental backups of Windows Guest Virtual Machines with BLIB enabled or Duplication of such images to MSDP/PDDO Storage Units fail with error - fbu_scan_buf: bytesNeeded already set

Article:TECH210289  |  Created: 2013-09-05  |  Updated: 2013-12-16  |  Article URL http://www.symantec.com/docs/TECH210289
NOTE: If you are experiencing this particular known issue, we recommend that you Subscribe to receive email notification each time this article is updated. Subscribers will be the first to learn about any releases, status changes, workarounds or decisions made.
Article Type
Technical Solution

Product(s)

Issue



BLIB (Block-level incremental backup)-based incremental backups processed by the plugin versions listed below may fail when writing to MSDP (Media Server Deduplication Pool) or PDDO (PureDisk Deduplication Option) based storage units with status code 84 (media write error) reported.

Similarly, duplication of BLIB-based incremental backups to MSDP/PDDO-type storage units from other tape or other disk pool types would fail with status code 84.  If the duplication job had only one image to duplicate, then the duplication job would exit reporting Status Code 191 (no images were successfully processed).


Error



An example of a failing duplication:

From the bptm log:
22:22:56.076 [6113] <2> 7:bptm:6113:nb5220-05: [DEBUG] PDSTS: fbu_check_imgheader: buf=0x0x2adc6c2bb000, buflen=65536, ih_magic=0x47f923e4 VMware vSphere
22:22:56.076 [6113] <2> 7:bptm:6113:nb5220-05: [DEBUG] PDSTS: fbu_check_imgheader: found FBU imgheader, fiid_fsize=23040
22:22:56.077 [6113] <2> 7:bptm:6113:nb5220-05: [DEBUG] PDSTS: fbu_check_imgheader: setting svh_minfile_size to FBU specific setting of 16384
22:22:56.077 [6113] <2> 7:bptm:6113:nb5220-05: [DEBUG] PDSTS: fbu_check_filheader: buf=0x0x2adc6c2c0c00, buflen=41984, streamoffset=2382848, next_streamoffset=2382848
22:22:56.077 [6113] <2> 7:bptm:6113:nb5220-05: [DEBUG] PDSTS: fbu_check_filheader: buf=0x0x2adc6c2c0c00, buflen=41984, streamoffset=2382848, fh_magic=0x7cf01bdc, meta_length=190928, filenum=2182, f_type=2, fsize=12.2147483648
22:22:56.077 [6113] <2> 7:bptm:6113:nb5220-05: [DEBUG] PDSTS: fbu_check_filheader: bytesNeeded=190976

After applying the fix, a larger buffer size (buflen=262144) is used to process the data stream.

An example of a successful duplication:

From the bptm log:
09:19:23 [32096] [32096] [DEBUG] PDSTS: fbu_check_imgheader: buf=0x0x2ad1e271b000, buflen=262144, ih_magic=0x47f923e4 VMware vSphere
09:19:23 [32096] [32096] [DEBUG] PDSTS: fbu_check_imgheader: found FBU imgheader, fiid_fsize=23040
09:19:23 [32096] [32096] [DEBUG] PDSTS: fbu_check_imgheader: setting svh_minfile_size to FBU specific setting of 16384
09:19:23 [32096] [32096] [DEBUG] PDSTS: fbu_check_filheader: buf=0x0x2ad1e2720c00, buflen=238592, streamoffset=2382848, next_streamoffset=2382848
09:19:23 [32096] [32096] [DEBUG] PDSTS: fbu_check_filheader: buf=0x0x2ad1e2720c00, buflen=238592, streamoffset=2382848, fh_magic=0x7cf01bdc, meta_length=190928, filenum=2182, f_type=2, fsize=12.2147483648
09:19:23 [32096] [32096] [DEBUG] PDSTS: fbu_check_extents: entry: buflen=238544, streamoffset=2382896, fm_len=190928, fm_nns=1, fm_nxext=4755


Environment



Deduplicating VmWare Incremental Backups that have Block Level Incremental Backups (BLIB) attribute enabled Deduplication Plugin versions:

  • NetBackup Media Server versions 7.5.0.1 through 7.5.0.6
  • NetBackup 5220 Appliance media server versions N 2.5, 2.5.1, 2.5.2 and 2.5.3

 


Cause



Plugin initialized a buffer (buflen=65536) that was insufficient to hold the amount of data that needed to be read (bytesNeeded=190976).  This issue was noticed in rare circumstances for guest Virtual Machine backups that had the BLIB attribute selected in the policy.


Solution



The formal resolution for this issue (Etrack 3242438) is included in the following releases:

  • NetBackup 7.5 Maintenance Release 7 (7.5.0.7)
  • NetBackup Appliances 2.5 Release Update 4 (2.5.4)

These releases are now available.  Download links can be found in the Related Articles below.

Workaround:
Please contact Symantec technical support, referencing this document and Etrack 3242432 to obtain an Emergency Engineering Binary (EEB) bundle containing a fix for this issue.


Supplemental Materials

SourceETrack
Value324238
Description

Duplication of Windows Guest VM INCR backups with BLIB enabled from AdvancedDisk to MSDP fail with plugin error - fbu_scan_buf: bytesNeeded already set


SourceError Code
Value84
Description

media write error


SourceError Code
Value191
Description

no images were successfully processed




Article URL http://www.symantec.com/docs/TECH210289


Terms of use for this information are found in Legal Notices