[Glass] Backup procedure

Otto Behrens via Glass glass at lists.gemtalksystems.com
Fri Jul 29 03:27:52 PDT 2016

>         And if i right understand i can switch from master to slave in real time ( some minutes? ).

When you need to activate your slave, you
1. stop the logreceiver
2. SystemRepository commitRestore

This is really quick (a few seconds)

3. Switch over your web server to talk to the slave. Here you may have
to think a bit how you want to do it. If your web server is on master,
you may have to do a DNS change (if the master machine is dead). If it
is alive, you can route traffic to the slave using the firewall or
some other way.

>         But it required some hardware and .... configuration.....
>         I think to use it to very 24x7 maximum guarantee system and continuity of service.

Yes, I think it is a decent solution. There is no absolute guarantee
though. You have to be sure that the logsender / receiver have caught
up all the log entries and you may have switched over on a point where
you lost a last transaction.

>         Restore the system to the last tranlog backup is not sufficient.
>         As the customer can realign the system if the last backup tranlog is 30 minutes old?

I don't really get what you're saying here.
If you have the tranlogs on master, then you can replay until the last
transaction, when your system comes back up.
If your tranlogs are lost on master but you restart with the existing
extent(s), you may have lost transactions.
If you have a hot standby in place, you are as up to date as you can
be if you lose tranlogs on master.

If not losing tranlogs on master is really critical, I'll consider
RAID and what other "safe" disk options you can get to store your
tranlogs on. Gemstone also has a replicate tranlog directory which you
can mount on a remote machine or something else.

>         Where i found the last 30 minutes transaction if the server is dead?

On the hot standby

>         I think having an intermediate solution could resolve many situations.
>         Having the ability to have a online copy of the active tranlog on the backup system it's a very good solution.
>         Is possible use the logsender / logreceiver only to replicate the current logs on the backup system ?

If I did run a hot standby, I do not worry about replicating tranlogs
because this is what the logsender / receiver does

>         With this support and the last  production backup  it's possible restore the system without losing any transactions.
>         But these are my considerations.....
>         Thanks,
>                 Dario
>> On Thu, Jul 28, 2016 at 7:55 PM, Bob Tucker via Glass
>> <glass at lists.gemtalksystems.com> wrote:
>>> We keep a warm recovery DB for our production GS system on a geographically
>>> separate system.  Nightly we restore the recovery DB from the latest prod
>>> backup, then as we switch tranlogs (script via cron) we have scripts that
>>> will package it up, send it over to the restore system, kick off scripts on
>>> that side that will prepare the tranlog and apply it to the warm recovery
>>> system.  Both sides are on AIX and we use rcp to move the files.  You cannot
>>> copy active tranlogs nor extents (we use raw) so requires the backup written
>>> to disk and exporting tranlogs to filesystems to be able to move them over.
>>> We are on a fairly old version so newer versions may be more robust.
>>> On Thu, Jul 28, 2016 at 1:00 PM, Trussardi Dario Romano via Glass
>>> <glass at lists.gemtalksystems.com> wrote:
>>>> Ciao,
>>>> some time ago ( 10 marzo 2016  ) Dale wrote :
>>>> Regarding risk of losing data on system restart ... you should already be
>>>> keeping copies of your backup files and tranlogs on a separate system, so
>>>> that if you lose a disk, you have fairly recent copies of both ... if you
>>>> are concerned about losing as little data as possible, you might think about
>>>> copy tranlogs to a separate machine several times a day ...
>>>> OK, i working in this direction.
>>>> I have some doubts:
>>>> A)  I need a external script  for create the new tranlog  every hour with
>>>> the  System class >> startNewLog.
>>>> In general i have some methods to perform at regular time and data but i
>>>> don't understand if i can schedule it directly into the gemstone,
>>>> or if i need external scripts call by Crontab?
>>>> B) On LAN i have a Windows system for perform ftp copy from the Gemstone
>>>> server to the backup system.
>>>> ( i use the Cobian program )
>>>> Now i think to setup the incremental  ftp copy of the  /tranlogs  server
>>>> directory.
>>>> But how does the ftp command by copying the online tranlog ?
>>>> Can create problematic on the server?
>>>> C) Link to my last email :   [Glass] Integrity of the system
>>>> I read about Warm and Hot Standbys
>>>> Is not possible have the " online copy " of the current  tranlog on the
>>>> backup system ?
>>>> Where for online copy i think the copy at the last transaction ( update at
>>>> the last minute?! ) on the server.
>>>> If this would be possible, when the server crash, on the backup system i
>>>> found the tranlog update to the latest transactions.
>>>> Is not bad?
>>>> Am I asking too much?
>>>> Thanks for any considerations,
>>>> Dario
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>>> --
>>> -B-
>>> "Think of how stupid the average person is, and realize half of 'em are
>>> stupider than that"
>>> - George Carlin
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