[Voyage-linux] help with sync scripts

[Robert Rawlins - Think Blue]

Hey Hermann,

Thanks for taking the time to explain that to me, that makes perfect sense!
I understand what you're saying!

That proposed solution you talk of certainly sounds good, so the ./sync
folder is effectively copied over on boot rather than shutdown, that way of
the power is lost then the synced copy of the folder will be restored when
the system next comes back to life rather than needing a proper
shutdown/reboot.

I'm more than happy to test some sync script ideas if you have any on how
that might work, sounds like a very nice option. Unless of course Punky has
a good reason for not implementing it into the build, which he may have.

Rob


-----Original Message-----
From: Hofer, Hermann [mailto:h.hofer at ahsnet.de] 
Sent: 18 November 2009 12:10
To: Robert Rawlins - Think Blue; voyage-linux at voyage.hk
Subject: RE: [Voyage-linux] help with sync scripts

Hi Rob,

all data will by synced to CF with 'voyage-sync sync', but be care ONLY in a
special directory '/.sync/...'. Syncing directly to '/var/log' as example in
a running system is not possible. If you call 'voyage-sync sync' and
simulate a power outage, all your saved data is available under this
directory until 'voyage-sync stop' ist called. With this option all data
from ramdisk is synced to '/.sync/...', any process accessing this fs is
killed, the directory gets unmounted from RAM and then a sync from
'/.sync/var/log' to '/var' on CF is executed. So only if voyage-sync with
option 'stop' is called your data gets sync to the correct place on the CF
but also any process accesing this fs will get killed, so this should only
be an option on shutdown. 

I belive it should possible to extend voyage-sync to detect a reboot with
data remaining in '/.sync/...' from a previously sync and copy this data
over to the correct place before syncing and mounting to ramdisk. If there
is interest I can help.

Also I will send Punky a diff to extend voyage-sync (from experimental) with
additional output to show this behaviour.


regards,
 Hermann

-----Original Message-----
From: voyage-linux-bounces+h.hofer=ahsnet.de at list.voyage.hk
[mailto:voyage-linux-bounces+h.hofer=ahsnet.de at list.voyage.hk] On Behalf Of
Robert Rawlins - Think Blue
Sent: Tuesday, November 17, 2009 11:50 AM
To: voyage-linux at voyage.hk
Subject: RE: [Voyage-linux] help with sync scripts

Hey Rodney,

Thanks for the reply, I appreciate your help on this. I've just tried
running that command as suggested and it doesn't really appear to make any
difference, it still doesn't actually save the changes onto the card until a
shutdown occurs.

Do you have any other suggestions? I'm sure we must be fairly close to
having a solution, seems wierd that their isn't a script for saving the
changes to the solid state, I'd have thought this would be helpfull to a lot
of people.

Rob

-----Original Message-----
From:
voyage-linux-bounces+robert.rawlins=thinkbluemedia.co.uk at list.voyage.hk
[mailto:voyage-linux-bounces+robert.rawlins=thinkbluemedia.co.uk at list.voyage
.hk] On Behalf Of rodney at optimail.com.au
Sent: 17 November 2009 01:53
To: voyage-linux at voyage.hk
Subject: Re: [Voyage-linux] help with sync scripts

Robert,

 looking through voyage-sync: despite the word 'sync' appearing throughout,
 I think it isn't actually doing a file system sync, it is just copying
 the writeable layer (tmpfs/aufs) to the underlying layer e.g. flash drive.

 That may not sync for some time, or shutdown.

 How about doing this for an experiment:
remountrw
/etc/init.d/voyage-sync sync
sync
remountro


Rodney


Robert Rawlins wrote:
...
# apart from /var/tmp and /var/log, add extra directories to sync from tmpfs

VOYAGE_SYNC_DIRS="/etc/thinkblue"

And this appears to work well, any changes in this directory are committed
to the disk on reboot. However, trying to sync this directory manually like
follows:

remountrw
/etc/init.d/voyage-sync sync
remountro


The commands run just fine, however, if I then simulate a power loss by
pulling the plug and restarting the system then the changes are not there
when the system comes back to life.
...

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