Hi everyone,
I wrote an e-mail regarding this issue before Christmas and had some good
replies - Thanks to all. However, we were still unable to solve the issue.
We decided to upgrade from 2.0.3 to 2.4.2 (using Ubuntu packages from
Hardy-Backports) to see if we could get it solved.
Unfortunately, it didn't solve the slow migration to tape issue. We had a
suggestion from Ulrich to move spooling to another RAID array, which can't
be done at the moment. So I'm looking at other solutions (if possible).
Here is a recap of our situation:
- Backups are taken from network clients to the Director/SD hard disk
(RAID0, with MySQL on the same array) and then later migrated from disk to
Tape (LTO3 with hardware compression)
- When migrating, it takes hours to write some MB to the tape (i.e. 1h45mins
for 5MB, with a rate of 0.9KB/s)
- I tested the Tape drive with dd and have good throughput, around 135MB/s.
Related to that, I have 2 questions:
Question 1:
When I do a migration to tape, while the first job is migrated, I'm
executing "status storage=Tape" and I see something like the following
output:
--snip--
Device status:
Autochanger "Autochanger" with devices:
"IBM-ULTRIUM-TD3" (/dev/nst0)
Device "FileStorage" (/backup/bacula) is mounted with:
Volume: WeeklyFileVolume-0002
Pool: *unknown*
Media type: File
Total Bytes Read=159,528,829,516 Blocks Read=1,360,087
Bytes/block=64,512
Positioned at File=57 Block=2,323,636,495
Device "IBM-ULTRIUM-TD3" (/dev/nst0) is mounted with:
Volume: 000014L3
Pool: Weekly Tape Pool
Media type: LTO-3
Slot 4 is loaded in drive 0.
Total Bytes=87,741,932,544 Blocks=0 Bytes/block=64,512
Positioned at File=0 Block=1
--snip--
>From "FileStorage", the "Total Bytes Read" always go over the "Total Bytes"
in the "IBM-ULTRIUM-TD3" section. Why is that? Isn't supposed to be the same
total in both section? It seems like the following is happening:
1. Read and write to tape (I've done the math, and write speed is around 3
GB/min there?!)
2. When job writing is done, the FileStorage read continues (I think this is
where we have a problem)
3. When reading is done, "Migration OK" e-mail report is sent, showing poor
stats about duration and speed rate.
Can someone explain that to me?
Question 2:
Would spooling help in our situation? Or it is just a waste of Disk I/O
since it is a migration from local hard disk to Tape Drive and not backup
from a network client directly to Tape?
Thanks for you help, very appreciated!
J-P
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