Thread: Migration and snapshot of database
I want to migrate physical server on to virtual machine
My physical server consist of
1. Some Application.
2. PostgreSQL Database
Here the system migrated from Physical machine will be replicated into two
VM's.
- One will be act as live machine, on which live operations will be performed.
- Second will be test VM, where I can make changes in application and test for
new features.
Both VM need to have their own database. But two copies of database require
twice the storage.
I want to optimize for storage.
Once the database is migrated to new machine, how I can use this database for
both VM's without two independent copies.
Test VM will have its own write operations, which will be ignored later.
My approach
Migration:
-I am thinking of using pg_basebackup for online database backup from physical
machine to new machine.
-Is pg_barman or pg_rman is faster than pg_basebackup?
Storage optimization:
I want to use snapshot to optimize for storage.
- Will take snapshot of original database and export the snapshot with
read/write access to test VM.
Since, I could not found anything within postgres, I plan to do it using file
system or LVM.
So with this method I can do my testing and delete the snapshot after testing
is done without reflecting original database.
Has anyone work on such scenario? What are problem faced in writable
snapshot?
On Thu, May 30, 2013 at 5:49 PM, aarti sawant <aartisawant0@gmail.com> wrote:
> I want to migrate physical server on to virtual machine
> My physical server consist of
> 1. Some Application.
> 2. PostgreSQL Database
>
> Here the system migrated from Physical machine will be replicated into two
>
> VM's.
> - One will be act as live machine, on which live operations will be
> performed.
> - Second will be test VM, where I can make changes in application and test
> for
>
> new features.
>
> Both VM need to have their own database. But two copies of database require
>
> twice the storage.
> I want to optimize for storage.
>
> Once the database is migrated to new machine, how I can use this database
> for
>
> both VM's without two independent copies.
> Test VM will have its own write operations, which will be ignored later.
>
> My approach
> Migration:
> -I am thinking of using pg_basebackup for online database backup from
> physical
>
> machine to new machine.
> -Is pg_barman or pg_rman is faster than pg_basebackup?
>
> Storage optimization:
> I want to use snapshot to optimize for storage.
> - Will take snapshot of original database and export the snapshot with
>
> read/write access to test VM.
>
> Since, I could not found anything within postgres, I plan to do it using
> file
>
> system or LVM.
> So with this method I can do my testing and delete the snapshot after
> testing
>
> is done without reflecting original database.
>
> Has anyone work on such scenario? What are problem faced in writable
>
> snapshot?
>
So, something like following?
1) Take a base backup of the cluster on the physical machine using
pg_basebackup.
2) Restore from it on the live VM and consider it the main cluster
instance from this point on.
3) Do something like: pg_start_backup('backup_label') -> take a
writable file system snapshot -> pg_stop_backup() -> copy
'backup_label' file to the snapshot.
4) Restore from the snapshot containing the backup_label file, use it
for testing, occasionally write to it and then discard the snapshot.
Since the snapshot is copy-on-write, the whole operation seems to
require less storage than otherwise (like a full base backup)
I am also eager to know if anybody has tried this and what are the
odds of this kind of setup being usable for usual master-slave
scenario possibly reducing cost of creating standbys?
--
Amit Langote