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Re: dump won't dump an fss snapshot on netbsd-5

Juergen Hannken-Illjes wrote:
On Mon, Jul 27, 2009 at 05:28:34PM -0400, Louis Guillaume wrote:
Hi Juergen,

Juergen Hannken-Illjes wrote:
On Sun, Jul 26, 2009 at 10:13:09PM -0400, Louis Guillaume wrote:
I just updated the machine connected to my tape drive from netbsd-4 (stable) to netbsd-5 (stable). Now dump will not back up my fss snapshots...
The /dev/fss? devices will not allow multiple opens.  To dump a snapshot
please use the -x / -X flags.  In your example it would be:

   dump -L maat-home -b 32 -0eautf /dev/nrst0 -x /var/tmp/maat-home /home

This appears to work properly, however I have no indication that a snapshot was made or even used aside from this:

[16:42:52 EDT] DUMP: Dumping a snapshot of /dev/rld0g (/home) to /dev/nrst0

Is it safe to assume that I don't have to create the snapshot with fssconfig first? And that dump takes care of that for us? It's not really clear in dump(8).

Yes and yes.  You could run "fssconfig -lv" and "systat vmstat" during
dump to see a fss device working ...

Another thing - fss in general (both via dump and by itself) is considered "experimental" but I haven't had much trouble with this until now. Is this because there has been limited testing? Limited resources to maintain/develop it? Perhaps it's not as stable on ports other than i386.

Limited testing. While I'm running snapshot dumps daily on all my
NetBSD machines I'm not aware of others using it on a regular basis.

I consider this a very important feature and would like to see it considered "stable". It would also be good to get rid of some ironic (albeit funny) documentation in the manual, such as:

  -x snap-backup
     Use a snapshot with snap-backup as backup for this dump.  See
     fss(4) for more details.  Snapshot support is experimental.  Be
     sure you have a backup before you use it.

... from the dump(8) page.

This is NOT meant ironic -- be sure you have a (non-snapshot) dump before
you try it.

Jeurgen - Thanks again. I do have one more curiosity...

Did something change in netbsd-5 that would break my old system of manually creating the snapshots with fssconfig, then backing them up?

While I am happy to do things the "right" way going forward, I have to wonder how come this worked doing it the other way in the past.

I've dumped/restored fss snapshots for years without dump -x. Actually, you helped me with this back in '05...

... Based on that I'm guessing that there was a change. Did we lose some flexibility here? The way it is now, I don't think I can make a snapshot now, and dump it later on when some other conditions are right. Not that I really need that, but it seems like a possible scenario.

At any rate - I now have good confidence in my backup system once again. dump works beautifully with -x. My backup script is simpler now too.

Please let me know if I can provide any testing or feedback that could help to get fss out of the experimental stage...


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