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Remedy AR System Server
AR System Mid Tier
Midtier, AR Server, Virtual Chat, SDK, java libraries in general
When a patch or hotfix is installed, there is usually the need to create a backup in case roll back is required.
Are there any recommendations on how to perform a backup to roll back?
It is a good practice to have a rollback for java applications.
Usually a java application is a series of libraries (jar, war ) and external resources such as images or configuration files.
The most complete method of backup would be to make a tar or zip file of the folder where the patch would be applied
There are benefits on doing this such as
1. A single file would have a full backup . preventing partial roll backs which will cause strange problems
2. A single backup could be historically kept allowing several roll back points
3. A single backup would be easier to move, restore, etc
1. Requiring more disk space (as jars are already compressed, so zip would not save too much disk space)
2. They may be bigger than individual files and in slow networks they can be transferred slowly
Another option would be to backup individual jars or libraries:
Smaller files, more granular among the benefits
This has the drawback of a partial rollback as monitoring multiple files is error prone. However, as long as these backups are properly done, they would provide a solid point in case rollback is needed.
Whatever option you choose, do not leave jar files in the same location as new files
my.old.jar (previous file)
my.veryold.jar (older file)
This is not recommended as the old jars even though they have a different name or double extensions may be loaded when the application is started, and this will cause very strange behavior that are usually hard to track.
Strange behavior may include errors never seen before or inconsistent behavior once a restart happens (as libraries may load in different order)
Once a backup is done. Place it somewhere else in your system or in your backup system, in that way it won't interfere with your new patch.
Here is a specific example of how to apply a midtier hotfix with easy rollback