[Opensim-users] Question on migrating database from Linux to Windows and vice versa

Chris Kennedy mewtwo0641 at cox.net
Mon Jul 12 12:53:27 UTC 2010


Thank you SO much for taking the time to explain it to me =) I sincerely 
appreciate it!
It has put my mind at ease about cross platform backups now... I was 
always worried I'd lose the stuff that I have worked long hours to put 
together on OpenSim by cross platform backups. I will continue to keep 
multiple backups though, mainly several "generations" of SQL dumps and 
OAR/IAR's , just to err on the side of caution. Thanks for the heads up 
on OS 0.7.x as well =)

On 7/12/2010 3:09 AM, Karen Palen wrote:
> My experience is with Engineering or design type databases rather than 
> commercial/SQL type of databases, however the concept of data 
> integrity is so fundamental that I would be very surprised if much 
> would happen without being noticed!
>
> In the case of MySql you are essentially running the same software in 
> different environments  - both the basic database server and the Admin 
> tools - so I would expect any major issues to be a very rare things.
>
> Probably the best assurance of this is the MySql "market share", it is 
> one of the most popular database systems in existence and is used in 
> all kinds of environments (OS, hardware, networks, etc.) from simple 
> standalone setups to massive distributed corporate "enterprise" 
> systems. As a result I would expect that any common problems would be 
> found and fixed very rapidly.
>
> The kind of data loss caused by parts of a file being deleted could 
> certainly occur, but there are very well known and widely used methods 
> to detect and fix this kind of problem. My recollection is that the 
> SQL "backups" from MySql have several built in mechanisms to check this.
>
> Loss of some more subtle information such as a pointer to a specific 
> texture (or your other examples) is more likely, however the 
> application software would (SHOULD!) be the same version of OpenSim in 
> both cases so this too is very unlikely. This however is a distinct 
> possibility when upgrading from one version to the next regardless of 
> the OS!
>
> Since there are extensive changes made to the internal workings of 
> OpenSim between V0.6.9 and V0.7.xx this becomes very plausible. It is 
> the subject of a lot of the testing work being done on the current RCs 
> as a result. Again I would expect that by the time V0.7 is released 
> the major problems either fixed or well known.
>
> All the same any grid that has more than a half dozen users will 
> likely implement its own beta testing program to catch these problems 
> in your specific environment. There always do seem to be a few issues 
> brought to light in these tests! Not a problem if you only need to fix 
> up two or three users (or regions) but if say 5000 users have their 
> inventory corrupted then you have a major problem!
>
> As always "slow and easy wins the race" and a well planned step by 
> step migration is essential.
>
> Karen
>
> On Sun, Jul 11, 2010 at 6:28 PM, Chris Kennedy <mewtwo0641 at cox.net 
> <mailto:mewtwo0641 at cox.net>> wrote:
>
>     I do make seperate OAR and IAR backups along side my SQL dumps =)
>
>     I was just wondering if there would be any definite data loss when
>     saving and restoring these SQL dumps across multiple platforms...
>     or if data loss would be a "freak" kind of thing (i.e. a bug in
>     the My SQL server or MySQL Admin when it comes to Linux or
>     Windows, or configuration differences between the default setup of
>     the MySQL server on Linux vs. Windows, etc).
>
>     Would it be a noticeable thing if data loss did occur such as
>     missing inventory, or something more subtle that would take a bit
>     of digging to find; such as missing textures or even "blank" data
>     (i.e. open a texture and all you see is a white box where the
>     texture should have been. Or try to play an animation / sound from
>     your inventory and it won't play)?
>
>     Thank you very much for the suggestions! =)
>
>
>     On 7/11/2010 7:25 PM, Karen Palen wrote:
>>     I don't have a lot of experience with porting MySql between
>>     different OSes, but general "belt and suspenders" considerations
>>     says that a second and independent path would be a very good
>>     "safety net".
>>
>>     I would definitely suggest making an IAR backup of every user
>>     inventory and an OAR backup of every region! In that way you have
>>     a totally separate way to transfer the data and at least the
>>     opportunity to recover anything which is corrupted or lost in the
>>     transfer!
>>
>>     I believe there are tutorials on how to automate these backups
>>     although I have not personally tried them. If you have more that
>>     2 or 3 users and/or 2 or 3 regions then this will significantly
>>     reduce the workload.
>>
>>     It pays to be VER conservative (careful) in making backups since
>>     if information is LOST it can be extremely hard to re-create,
>>     finding something in multiple backups is trivial compared to
>>     re-creating content!
>>
>>     remember: Jesus saves - EARLY AND OFTEN!
>>
>>     Karen
>>
>>     On Sun, Jul 11, 2010 at 4:22 PM, Chris Kennedy
>>     <mewtwo0641 at cox.net <mailto:mewtwo0641 at cox.net>> wrote:
>>
>>         Hi, I want to migrate my OpenSim MySQL database from Linux to
>>         Windows and vice versa (for traveling reasons) using the
>>         MySQL Admin's SQL dump ( MySQL Admin Backup) feature.
>>
>>         Is there anything special that I need to know or to look out
>>         for when doing this (besides making sure Max Packet Size is
>>         set to 16 MB on the target system)?
>>
>>         The way I normally do my database backup in the Linux
>>         environment is to shut down the OpenSim server, go to the
>>         backup tool in MySQL Admin, create a backup project (if it
>>         doesn't already exist) for my OpenSim schema making sure all
>>         the tables are selected for backup. Then I go into advanced
>>         options and click on Normal Backup, and check Complete Backup
>>         and run the backup to save my database to a .sql file. This
>>         method has worked perfectly fine for me under Linux with no
>>         data loss after a restore from backup that I can tell. I have
>>         even restored my database to a Windows environment from a
>>         Linux created MySQL dump file with no problems that I can see.
>>
>>         My concern is creating a database backup in a Windows
>>         environment and then restoring it to Linux (or even another
>>         Windows environment). Would this, under normal circumstances,
>>         cause data loss?
>>
>>         The reason I ask is: I have successfully been able to restore
>>         my Windows created SQL dump file to Linux and other Windows
>>         systems running XP... But the moment I try to restore my
>>         database to a Windows 7 system I get an error that says
>>         "Object Type not recognized" (or it might have said Object
>>         Type not Found, I don't remember off the top of my head) and
>>         the restore fails.
>>
>>         In a nutshell, is it safe to port my backups between
>>         different operating systems like this? Or am I better off
>>         creating OARs of my regions and IAR of my inventory(s)? I
>>         always make both OAR/IAR and SQL dump backups just to be
>>         safe, but I would like to know.
>>
>>         Any suggestions and/or tips would be much appreciated! =)
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