SAN Client backups failing intermittently with STATUS 174
| Article:TECH147561 | | | Created: 2011-01-06 | | | Updated: 2012-08-18 | | | Article URL http://www.symantec.com/docs/TECH147561 |
Problem
In certain circumstances SAN Client backups can fail with STATUS 174, if the client have utilities or programs which use a Test Unit Ready (TUR) commands whilst data is being sent via the SAN/Fibre. This can cause sequence errors in the Fibre Transport (FT) communication, which will cause the backup to fail because of unexpected data being received by the media server.
Error
Job details
Critical bptm(pid=xxxxx) data buffers out of sequence, expected number 1842595, received 1842598 <<<---Received number is higher
Critical bptm(pid=xxxxx) data buffers out of sequence, expected number 17, received 20
BPTM log
11:44:35.144 [5167] <32> write_data: data buffers out of sequence, expected number 17, received 20
11:44:35.144 [5167] <2> write_backup: write_data() returned, exit_status = 174, CINDEX = 0, TWIN_INDEX = 0, backup_status = -8
NBFTSRVR (OID:199) log
06/22/09 11:44:34.297 [Debug] NB 51216 FATServer 199 PID:7667 TID:4124814240 File ID:199 [No context] 1 [ProcessReadWrite] BUFFER sequence error, cmd = 0x0x3b, pipe = 0x0x1, ftseq = 0x0x10, rseq = 0x0x13, state = 0x0x1
06/22/09 11:44:34.297 [Debug] NB 51216 FATServer 199 PID:7667 TID:4124814240 File ID:199 [No context] 1 [ProcessReadWrite] WRITE BUFFER sequence error 16 19
Environment
NetBackup 6.5.6, SAN Client backups
Cause
The TUR commands can be sent when clients have multi-pathing or other monitoring software
Solution
The official resolution currently, is to determine what is causing the TUR commands and to prevent then from occurring.
Workaround
Symantec Engineering (Etrack:1736627) have adjusted the NetBackup code from NetBackup 6.5.6 to include a new touch file ( /usr/openv/var/FTCLIENT_VALIDATE_VIA_CHECK_CONDITION ). This touch file needs to be created on the client(s) experiencing the STATUS 174 failures. After the touch file is created (NetBackup FT client service requires a restart), additional Client Data Block (CDB) information is supplied which counteracts the problems when the additional TUR data is sent. Unfortunately, there will be a slight reduction in performance as the CDBs are sent twice.
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| Source | ETrack |
| Value | 1736627 |
| Description | Periodic data buffer sequence failures backing up Linux clients |
Article URL http://www.symantec.com/docs/TECH147561
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