[Glass] Integrity of the system

[Trussardi Dario Romano via Glass]

Ciao Behrens,

	thanks for your considerations.

>> When Dale wrote:  " if you are concerned about losing as little data as
>> possible, "
>> 
>> i'm scared.
>> 
>> My system is very small but if i think to complex system, i can't not losing
>> data, not any transaction.
>> 
>> I have not experienced, and maybe I worry too much, but i 'need'  a system
>> where losing data  it is a very, very remote possibility.
>> 
>> In the last year i don't have any problem on the server ( run 24x7 )  but i
>> need to clarify the situation.
>> 
>> Some experience? considerations?
> 
> I think Dale's concerns are related to disk / hardware failures. I do
> not think that these possible concerns are a GemStone specific thing.

Of course, i think at disk, hardware failures or a restart problematic ( after a shutdown the system don't start )

In any case i need to have the backups data:

		1) the last repository backup ( do every night ) 
	
		2) the relative old tranlogs  ( create after the last repository backup  )

		3) the "copy" of the current tranlogs ( the last tranlogs updated to the latest transactions )

	for restart ( in each case ) a new system with data update at the latest transactions.

	For point 1 - 2 i think a disk,  where regularly save their related files.

	For point 3 i think a 'online copy' of the last tranlogs, but i  do not know how to handle such a solution.

> If you throw quality hardware at it, with RAID 5 and UPS (as you've
> mentioned) and what not (quality server components, disks, RAM, etc),
> then you're doing well to protect your transactions from being lost
> (regardless of what software system you are running). You can even go
> further with fancier hardware that replicates disks across a SAN disk
> solution, etc.

I don't know about SAN disk solutions, the only know is the limited budget.

> If you do the hot standby thing you protect yourself more by doing a
> GemStone transaction log replication as and when transactions are
> written (no realtime guarantees though).

In some my solutions the hot standby is not required ( i can't have another PC for do it )

I need only to replicate somewhere the online tranlog.

> 
> If you copy your tranlogs to another server before rebooting, then
> you're more safe from losing the files if the disk does not come back
> after the reboot.

OK, i can do it if i'm linked to the server.

But if the system go down in the night after a power cut ?

> 
> In the 20 years that I've worked with GemStone, in 4 different
> installations, we've not lost data because of malfunction of GemStone
> software.
> 
> Now that deserves some kudos.

	+10

> -----------------------------------------
> 
> We run our extent files in RAM, write tranlogs to disk (no RAID or
> anything) and run hot standbys in a different data centre. On hot
> standby we write the extent and tranlogs to disk. I believe that
> running a production extent in RAM reduces probability of failure
> because our databases do a load of random reads, which will wear a
> mechanical disk more easily than RAM.
> 
> We have not had a failure in 8 years (and currently 8 live systems).
> 
> I hope this gives you some comfort.

I am sure and confident.

I just have to focus on the issues, and understand the best solutions.

Thanks,

	Dario

P.S. You can found some my points of view in my last emails:	Re: [Glass] Backup procedure