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DragonFly users List (threaded) for 2010-04
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Re: Disabling snapshot symlinks during manual snapshot

From: Siju George <sgeorge.ml@xxxxxxxxx>
Date: Fri, 23 Apr 2010 12:01:54 +0530

On Fri, Apr 23, 2010 at 2:22 AM, Matthew Dillon
<dillon@apollo.backplane.com> wrote:
> :For a MS Windows user it will look like the actual pic below.
> :
> :http://picasaweb.google.com/sgeorge.ml/OpenBSDDesktop#5462824618389365522
> :
> :Clicking on the snapshot Directory they can get the snapshot contents :-)
>    I am totally amazed that it actually works.  Wow, very cool.  Talk
>    about instant gratification!

Actually Every developer here was amazed that this can be done :-)
You should have seen the smiles on their faces.

I share the database also the same way.

1) Take SQL dumps split into files for each database on the
development server every 1 hour using the script


rm -f /var/mysql-1hBak/*
mysql -u root -pmy\$qlPW-whatever -N -B -e 'show databases' | while read; do
   mysqldump -u root -pmy\$ql -e "$REPLY" > /var/mysql-1hBak/$REPLY.sql; \

2) rsync it to a pfs in  dragonfly server and snapshot it every hour (
15 mins after mysqldump cron runs on the development server )

3) Share the snapshots directory and the pfs inside it using samba.

And the big concerns for people was the huge amount of space requierd
to do this and the network tracffic this will generate.

I checked it and found that there is only negeligible in this case

The file system is only 65% full so I guess there is not much need to worry.

This came as a big surprise to all and Every one wanted to kwow how I
acheived it.
So I gave the lecture  " You DragonFly BSD's  file system called
hammer  can remember file system history......" :-)

The network traffic is also low because the changes in files that
takes place in every 5 minutes interval is quite trivial :-)

>    Yes.  So, for example, if you were to set prune-min to 5d then
>    no pruning will be done for the most recent 5 days worth of
>    fine-grained history, regardless of what the snapshot interval
>    is set to.  Thus you can safely access fine-grained transaction
>    ids within the last 5 days.  Beyond 5 days, however, you have to
>    use the snapshot transaction ids from the softlinks and/or snapls.
>    This has not been well tested but that was the intent of the
>    directive.

Yes I understood that from the man page.

What I was asking is if there is a way post snapshot if the file
system histroy is retained for a previous time.

I mean if it is Fri Apr 23 11:59:19 IST 2010 now.
I have prune-min for a pfs as 2d but only take daily snapshots as
20:30 every day

Can I create a snapshot link that will give me the file system state
for yesterday 14:30 ?

Thanks :-)


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