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For the undo tablespace and the temporary tablespace, sufficient space should be calculated so that there are no operational problems.

Backup space of Disk DB

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For more detailed information related to backup, please refer to the "Altibase Backup and Recovery Guide" document. This section only explains the part of calculating the capacity related to backup.

Altibase must be operated in archive log mode for backup, and two disk spaces are required for this backup.

Archive log file directorySpace to store backup files of online log files
Backup spaceSpace of data files to be stored with online backup, etc.

In the case of backup space, it can be calculated as the sum of the estimated memory DB and disk DB capacity.

Since there are various types of backups such as the type of backing up the entire DB every time, the type of incremental backup, and the type of tablespace unit backup, it is recommended to calculate the appropriate space for each backup.

In the case of the archive log file directory, it is safe to delete all previous log files that are not referenced after the user completes the backup.

Therefore, it can be said to be flexible according to the backup policy because the log file capacity to be stored may differ according to the backup cycle and policy.

Let's look at the following example. In the example below, the backup policy is assumed on a daily basis.

 
Memory DB
Disk DB
Amount of online log files per day
Estimated capacity20GB500GB200GB
Space required for backup20GB500GB200GB (archive)
Space considering the last backup20*2 = 40GB500*2 = 1TB200GB * 2 = 400GB
  • Memory DB is stored as one pair (two files) at the checkpoint, but only one stable file is backed up at the backup stage, so it must be considered the backup space as much as the memory DB capacity.
  • If the disk DB is assumed to be a full backup policy, backup space is required as much as the expected disk DB capacity.
  • Since archive log files must be stored until the next backup occurs, all archive log files created during the backup cycle must be stored since the previously backed up can be used to restore the current point in time.
  • In terms of the backup cycle concept, the previous backup copy can be deleted only after the current backup is successful. If the last backup copy is kept on the disk, twice as much space for backup is required.

Considerations when using backup with iLoader

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In addition to the online backup method, if it is necessary to additionally backup each table, the user can use a utility called the iLoader to back up the table as a text file.

In this case, the capacity of the data file backed up with the iLoader should be considered when calculating the disk capacity.

Generally, since a data separator of about 5 bytes should be used for each column, space obtained by the following arithmetic is required in addition to the actual expected disk DB capacity.

 

  • Separator capacity = 5 bytes * number of records * number of columns

Example> If there are 1 million data in a table with 10 columns, 5 * 10 * 1,000,000 = 50MB is additionally required. 

 

In other words, it means that the discriminator capacity is required in addition to the initially calculated disk DB capacity.

In addition, even when compressed and stored in a disk, the size of the space to be stored must be calculated in consideration of the compression ratio compared to the capacity calculated above.

This part is not added to the disk capacity calculation example below, so be sure to take this into account when users choose this backup method.

Example of disk capacity calculation

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Item
Capacity
 
Disk DB data file500GB500GB
Data file of disk DBSpace required as much as disk DB capacity 
Memory DB data file20G20*2 = 40GB
Data file of memory DBMemory DB capacity * 2 space required 
Backup fileMemory DB capacity + disk DB capacity 
Backup fileMemory DB + Disk DB + Archive Log File560GB
Calculation exampleUsageRequired disk space
Archive log fileThe amount of online log files to be saved during the backup cycle 
Archive log file40GB40GB
Online log file20GB (varies according to system size) 
Online log file20GB20GB
Total space required40+500+20+40+(560*2)1,720GB

 

Network capacity calculation

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The network capacity calculation part of this document only considers the replication. The user must calculate the network capacity by considering the service network, and the replication network capacity covered in this document must also be added to the total network capacity.

Packet size due to replication

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In the case of sending packets in the replication, the following calculation formula is able for each transaction type.

Type
Size(byte)
INSERT헤더(28byte) + (데이터길이(4byte) + 데이터(x))
UPDATE

헤더(32byte) + (PK데이터길이(4byte) + PK데이터(x)) + (변경 전 데이터 길이(4byte) + 변경 전 데이터(x)) + (변경 후 데이터 길이(4byte) + 변경 후 데이터(x))

DELETE헤더(28byte) + (PK데이터길이(4byte) + PK데이터(x))
Commit / Rollback16byte

위와 같이 각 트랜잭션 별로 기본적인 헤더를 가지고 있으며, 전송되는 데이터에 대하여 컬럼별 길이 정보와 실 데이터의 길이를 모두 합산한 크기만큼 패킷을 전송한다.