SAN base VMware restores using VDDK version 5 complete with Status 0, however nothing was restored.
| Article:TECH179716 | | | Created: 2012-01-24 | | | Updated: 2012-01-24 | | | Article URL http://www.symantec.com/docs/TECH179716 |
Problem
NetBackup 7.1.0.3 and 7.5 restores may complete with Status 0, however if the SAN LUN was offline nothing was restored. This is due to a known VMware issue with VDDK version 5, where VDDK does not return an error for offline LUNs.
Error
VxMS:
Begin::vfm_write [01/13/2012 19:18:15.0821 : ]
Input: nreq=1
vfm_obj_t { obj_name = 0x0000000006FA99C0 obj_orig_name = [DATASTORE1] vmclient01-RESTORE/vmclient01-RESTORE.vmdk obj_print_name = [SAN A vol 4: RAID 6] vmclient01-RESTORE/vmclient01-RESTORE.vmdk }
[ I/O Req ]
vfm_io_req_t { io_offset = 0 io_reqlen = 18432 io_bufp = 0x0000000007367380 io_bytes_trans = 0 io_bytes_req = 0 io_error = 0 }
01/13/2012 11:18:15.0821 : write:h:\7103\src\vxms\plugin\common\map\vix\VixFile.h:231 <INFO> : Entered. offset(0x0000000000000000), len(0x0000000000004800)
01/13/2012 11:18:15.0821 : write:h:\7103\src\vxms\plugin\common\map\vix\VixFile.h:243 <INFO> : Calling vdWrite(sector_offset = (0x0000000000000000), sector_count = (0x0000000000000024))
01/13/2012 11:18:15.0837 : g_vdInterfaceLogger:.\libvix.cpp:1683 <INFO> : diskLibPlugin: 2012-01-13T11:18:15.837-08:00 [04660 error 'Default'] Incomplete write to, Wanted 20480 Got 0
01/13/2012 11:18:15.0837 : write:h:\7103\src\vxms\plugin\common\map\vix\VixFile.h:278 <INFO> : Exiting normally
Output:
[ I/O Req ]
vfm_io_req_t { io_offset = 0 io_reqlen = 18432 io_bufp = 0x0000000007367380 io_bytes_trans = 18432 io_bytes_req = 0 io_error = 0 }
End:: result(0)
Environment
Issue can be found in:
NetBackup 7.1.0.3 and 7.5, or any version where VDDK version 5 is installed.
Cause
VDDK 5.0 does not return error for SAN writes to offline LUN.
http://www.vmware.com/support/developer/vddk/VDDK-500-ReleaseNotes.html
When attempting SAN transport writes to virtual disk on an offline LUN, write operations appear to succeed despite the LUN being offline. Specifically, the VixDiskLib_Open() function returns success because the LUN is exposed to the program, but VixDiskLib_Write() fails to return an error even though it cannot write to an offline LUN. For backup and restore software running through a proxy, this issue causes restores to return success, when nothing is actually written to virtual disk. VDDK 1.2.1 did return an error when attempting writes to an offline LUN, so this is a regression. When a LUN is offline, read and write operations should return an error. A fix has been identified and will be provided in a future release. Meanwhile, one workaround is to check if a LUN is offline before attempting a restore. An alternate workaround is to keep LUNs always in online mode.
Solution
Identify the offline or readonly LUN. This can also be seen if the LUN is uninitialized due to a misconfiguration in the zoning.
When using multiple paths, verify all paths are online or install the multipath application.
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Article URL http://www.symantec.com/docs/TECH179716
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