Prepare the directories required when creating instances.
Considerations when deploying resources
The disk configuration on the resource deployment destination is important, because it affects not only recovery following disk corruption, but normal operation as well. The points for determining the disk configuration are as follows:
If the backup data storage destination and the data storage destination are both lost, it will not be possible to recover the data, so deploy them to separate disks.
To shorten the recovery time following a single disk fault, deploy the system disk and data storage destination to separate disks.
The backup data storage destination requires at least double the capacity of the data storage destination, so deploy it to the disk with the most space available.
When large amounts of data are updated, the write-to load for the data storage destination, transaction log storage destination, and backup data storage destination (mirrored transaction log) will also be great. For this reason, deploy them to separate disks, out of consideration for performance.
Note
When using the volume manager provided by the operating system, be aware of which physical disk the file system has been created on, for example, by deploying the data storage destination and the backup data storage destination to separate disks.
Resource | Role |
|---|---|
Database cluster | The area where the database is stored. It is a collection of databases managed by an instance. |
Tablespace | Stores table files and index files in a separate area from the database cluster. |
Transaction log | Stores log information in preparation for a crash recovery or rollback. |
Archive log | Stores log information for recovery |
Corefile | Symfoware Server process corefile output when an error occurs with a Symfoware Server process. |
The following are examples of disk deployment:
Number of disks | Disk | Deployment |
|---|---|---|
3 | System disk | Symfoware Server program |
Corefile | ||
Connected physical disk | Data storage destination, transaction log storage destination | |
Connected physical disk | Backup data storage destination | |
2 | System disk | Symfoware Server program |
Corefile | ||
Data storage destination, transaction log storage destination | ||
Connected physical disk | Backup data storage destination |
To generate an instance using WebAdmin, we propose an optimum deployment that takes into account the status of all disks at the time of instance is generation, and item 1 to 3 in the "Considerations when deploying resources" subheading above, based on the criteria below (note that a different deployment can also be specified).
The mount point does not include national characters
The instance administrator has the proper permissions to read and write on the mount point
Information
Even if the mount point of each file system was deployed to a different partition or slice, it will still be verified if they are on the same physical disk.
If the operating system volume manager was used, it will not be verified if the file systems were created on the same physical disk.
Preparing directories
The directories to be prepared depend on the way that you create the instances.
The following shows the directories that need to be prepared:
Directory to be prepared | Using WebAdmin | Using the initdb command |
|---|---|---|
Data storage destination | Y (*1) | Y |
Backup data storage destination | Y (*1) | O |
Transaction log storage destination | O (*1) (*2) | O |
Corefile output destination | N (*3) | O |
Y: Required
O: Optional
N: Not required
*1: WebAdmin automatically creates a directory
*2: The default is to create in a directory in the data storage destination. When it is necessary to distribute the I/O load for the database data and the transaction log, consider putting the transaction log storage destination on a different disk from the data storage destination
*3: The default is to output to /var/tmp/symfo_Version/instanceAdmin_instanceName/core - to change it, configure the core_directory and the core_contents parameters in postgresql.conf (refer to "Parameters" in the Operation Guide for details)
Note
The directories must meet the following conditions:
The directory owner must be the OS user account that you want to be the instance administrator
The directory must have write permission
The directory must be empty
It is not possible to use a directory mounted by NFS (Network File System) when using WebAdmin.
The following example shows the OS superuser creating /database/inst1 as the directory for storing the database data and changing the owner of the directory to the OS user account "symfo".
# mkdir /database/inst1 # chown symfo:symfo /database/inst1 # chmod 700 /database/inst1
