---Guy
(via iPhone)
On 9 Mar 2011, at 01:22, Phil Stracchino <alaric AT metrocast DOT net> wrote:
> I just had a very odd (and rather alarming, for a few minutes) event happen.
>
> Five days ago, I received a new box of blank LTO2 tapes.
> On Sunday, I deleted the first six old LTO1 tapes from my FULL-TAPE pool
> and labelled six of the new LTO2 tapes, ARCH-0001 through ARCH-0006, in
> preparation for the full backups scheduled to begin at 0430 yesterday.
> The backups ran rather slowly, writing three tapes, ARCH-0001 through
> ARCH-0003, before eventually stalling at the writing-attributes stage.
> (I think I know why that happened. I'll come back to that later.)
>
> Late this morning, I eventually killed the stalled backups, deleted the
> jobs, purged the three tapes used, and marked them RECYCLE. Then I
> restarted MySQL and Bacula (more on that later), then restarted all the
> backups, by hand. The smaller backups ran to completion fine; the main
> server backup filled the first LTO2 tape not long ago and requested a
> second tape. It requested ARCH-0004, as ARCH-0004 is the first
> completely unused appendable volume. I have it set to ACCEPT ANY
> VOLUME, so I loaded the correct tape, ARCH-0002, and clicked Mount in BAT.
>
> This is where I had an adrenaline-rush moment, because after mounting
> the tape BAT storage daemon status reported the storage daemon as
> mounted WITH ARCH-0004. I double-checked to ensure that I had
> physically inserted ARCH-0002 into the drive, and sure enough, it was.
> The display did not update to correctly show the mounted volume as
> ARCH-0002 until Bacula wrote the first 5GB "file" to the tape. That
> gave me a few bad minutes. I did NOT want to have to kill the full
> backup and start it over.
>
> (The first tape always seems to be slow to fill, because many small
> files are written to it. It took seven hours to write 226GB of data to
> the first tape, an average of about half a gigabyte per minute. By the
> time Bacula gets into the second tape, it's into the big storage array
> which mostly contains multi-megabyte to multi-gigabyte files, and it's
> now writing about 1.3GB/minute.)
>
>
Are you spooling? If not you should try it. It will speed up your backs no end
and prolong the life of your tapes. Prevents the shoeshine effect.
> Now, I said I'd get back to the MySQL issues. I was reading through
> some documents about mySQL on ZFS, and came across (again) a
> recommendation from one MySQL tester that reported the best MySQL
> performance from setting the InnoDB buffer pool small, 100MB or so, and
> allowing ZFS to do the data caching. And I thought, "You know, I don't
> believe I've ever tried this. I'll give it a shot and see how it goes."
>
> Well, after trying this, I can now definitively state: DO NOT DO THIS
> IF YOUR BACULA CATALOG IS ON MYSQL. It may well work well for general
> usage, but for Bacula, this configuration trick DOES NOT WORK. If you
> are using Bacula with a MySQL catalog database on ZFS, configure MySQL
> as you would if it were NOT on ZFS. Do NOT rely on the "let ZFS cache
> the data" trick, because it won't work with Bacula.
>
>
>
> --
> Phil Stracchino, CDK#2 DoD#299792458 ICBM: 43.5607, -71.355
> alaric AT caerllewys DOT net alaric AT metrocast DOT net phil AT
> co.ordinate DOT org
> Renaissance Man, Unix ronin, Perl hacker, SQL wrangler, Free Stater
> It's not the years, it's the mileage.
>
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