Carousel is a LIE!

It's a race to the finish

25 Feb 2010

I mentioned that I've been having problems with Bacula recently. These have been aggravated by the fact that the trigger seems to be a job that takes 53 hours to finish.

Well, I think I've got a handle on one part of the problem. See, when Bacula is doing this big job, other jobs stack up behind it -- despite having two tape drives, and two separate pools of tapes, and concurrent jobs set up, the daily jobs don't finish. The director says this:

9279 Full    BackupCatalog.2010-02-20_21.10.00_10 is waiting for higher priority jobs to finish
9496 Full    BackupCatalog.2010-02-23_21.10.00_13 is waiting execution
9498 Full    bigass_server-d_drive.2010-02-24_03.05.01_15 is running
9520 Increme  little_server-var.2010-02-24_21.05.00_38 is waiting on Storage tape
9521 Increme  little_server-opt.2010-02-24_21.05.00_39 is waiting on max Storage jobs

but storage says this:

Running Jobs:
Writing: Full Backup job bigass_server-d_drive JobId=9498
Volume="000031"

pool="Monthly" device="Drive-0" (/dev/nst1)
spooling=1 despooling=0 despool_wait=0
Files=708,555 Bytes=1,052,080,331,191 Bytes/sec=11,195,559
FDReadSeqNo=22,294,829 in_msg=20170567 out_msg=5 fd=16

Writing: Incremental Backup job little_server-var JobId=9508 Volume="000017"

pool="Daily" device="Drive-1" (/dev/nst0)
spooling=0 despooling=0 despool_wait=1
Files=156 Bytes=3,403,527,093 Bytes/sec=72,415
FDReadSeqNo=53,041 in_msg=52667 out_msg=9 fd=9

Writing: Incremental Backup job little_server-etc JobId=9519 Volume="000017"

pool="Daily" device="Drive-1" (/dev/nst0)
spooling=0 despooling=0 despool_wait=0
Files=9 Bytes=183,606 Bytes/sec=3
FDReadSeqNo=72 in_msg=50 out_msg=9 fd=10

Writing: Incremental Backup job other_little_server-etc JobId=9522 Volume="000017"

pool="Daily" device="Drive-1" (/dev/nst0)
spooling=0 despooling=0 despool_wait=1
Files=5 Bytes=182,029 Bytes/sec=3
FDReadSeqNo=45 in_msg=32 out_msg=9 fd=19

Writing: Incremental Backup job other_little_server-var JobId=9525 Volume="000017"

pool="Daily" device="Drive-1" (/dev/nst0)
spooling=0 despooling=0 despool_wait=0
Files=0 Bytes=0 Bytes/sec=0
FDSocket closed

Out of desperation I tried running "unmount" for the drive holding the daily tape, thinking that might reset things somehow...but the console just sat there, and never returned a prompt or an error message. Meanwhile, storage was logging this:

cbs-01-sd: dircmd.c:218-0 <dird: unmount SL-500 drive=1
cbs-01-sd: dircmd.c:232-0 Do command: unmount
cbs-01-sd: dircmd.c:596-0 Try changer device Drive-0
cbs-01-sd: dircmd.c:617-0 Device SL-500 drive wrong: want=1 got=0 skipping
cbs-01-sd: dircmd.c:596-0 Try changer device Drive-1
cbs-01-sd: dircmd.c:612-0 Found changer device Drive-1
cbs-01-sd: dircmd.c:625-0 Found device Drive-1
cbs-01-sd: block.c:133-0 Returning new block=39cee10
cbs-01-sd: acquire.c:647-0 JobId=0 enter attach_dcr_to_dev

...and then just hung there. "Aha, race condition!" I thought, and sure enough a bit of searching found this commit in November: "Fix SD DCR race condition that causes seg faults". No, I don't have a segfault, but the commit touches the last routine I see logged (along with a buncha others).

This commit is in the 5.0.1 release; I wasn't planning to upgrade to this just yet, but I think I may have to. But I'm going on vacation week after next, and I'm reluctant to do this right before I'm away for a week. What to do, what to do...

Tags:

1 Comment

From: Kai
5 March 2010 03:31:23

With the backup, taking 2+ days to write a couple of TB to tape is going to cause problems - if not in software, then in hardware as the tape drive shoe-shines (I assume you're using LTO or DLT).



Is there any option to do a disk to disk to tape backup - can you get a LUN online on the backup server with a couple of TB on the cheap and dump the backup to that first? Can you sneakernet (or post) a couple of TB of data somewhere closer to the backup server than 100Mbs away?



Also, I don't know about Bacula, but can you interleave the backups, so the backup server is backing up other stuff at the same time, thereby keeping the tape drive occupied and streaming data happily?



Finally, if you're looking for another option for backup software (not open source) have a look at PresSTORE. http://archiware.com/

Add a comment:

Name and email required; email is not displayed.

Name (required)
Email (required)
Website
The site is named after Saint ________ the Carpeted: (required)
Comment

Related Posts