Zim Server Performance Tuning

To optimize Zim Server performance, it’s crucial to fine-tune the configuration settings in the zimconfig.srv file. Here are detailed technical guidelines for each of the three key factors:

1. Maximize Shared Memory Usage

Buffers and Areas Allocation: Increase the number of buffers and areas allocated in shared memory. This reduces the need for frequent memory allocation and deallocation, which can be costly in terms of performance.
- Configuration Options:
- SHARED_MEMORY_BUFFERS: Set this to a high value to ensure ample buffer space.
- SHARED_MEMORY_AREAS: Increase this to allow more areas to be stored in shared memory.
- Example: ini SHARED_MEMORY_BUFFERS=1024 SHARED_MEMORY_AREAS=256

2. Balance Shared Memory Usage

Avoid Over-Allocation: While maximizing shared memory usage is beneficial, it’s important not to exceed system-defined limits. Over-allocating can lead to overheads, such as increased context switching and memory paging, which degrade performance.
- Configuration Options:
- MAX_SHARED_MEMORY: Set this to a value that balances usage without exceeding system limits.
- SHARED_MEMORY_THRESHOLD: Define a threshold to prevent over-allocation.
- Example: ini MAX_SHARED_MEMORY=2048MB SHARED_MEMORY_THRESHOLD=80%

3. Reduce Input and Output Operations

Minimize I/O Operations: Excessive I/O operations can significantly slow down the server. Optimizing these operations can lead to substantial performance improvements.
- Configuration Options:
- IO_OPERATION_LIMIT: Set a limit on the number of I/O operations.
- CACHE_SIZE: Increase the cache size to reduce the frequency of I/O operations.
- Example: ini IO_OPERATION_LIMIT=1000 CACHE_SIZE=512MB

Additional Tips

Monitoring and Tuning: Regularly monitor the performance metrics of your Zim Server and adjust the configuration settings as needed. Tools like top, htop, or custom monitoring scripts can help you keep track of memory usage and I/O operations.
Documentation and Support: Refer to the official Zim Server documentation for detailed descriptions of each configuration option. If you encounter issues, consider reaching out to the Zim Server support community for advice and best practices.

By carefully adjusting these settings, you can achieve a well-balanced and high-performing Zim Server environment.

Checkpoint Buffers and Checkpoint Transactions

These options define the size of the checkpoint file, which is either the number of blocks or transactions that Zim Server will process before physically committing to disk. Both options refer to transactions that were effectively committed, meaning transactions that successfully finished.

Key Concepts

Optimized Checkpoint Mechanism: Zim Server’s checkpoint mechanism ensures that only the last occurrence of a block is written to disk. This means that larger checkpoint files can lead to more efficient performance due to reduced input and output operations.
Balancing Checkpoint Size: While larger checkpoint files can improve efficiency, they also mean that Zim Server will spend more time processing blocks and less time handling ongoing transactions. Additionally, larger checkpoint sizes can lead to longer wait times before the checkpoint file is produced and committed to disk.

Configuration Guidelines

To achieve optimal performance, it’s important to balance these options based on the size of your database and the number of users.

Small Databases

For small databases or a small number of users, use the following settings:

checkpoint buffers = 1000        # Small checkpoint file
checkpoint transactions = 100000 # Unlikely to reach this limit

Explanation: These settings instruct Zim Server to update the database files after 1000 blocks are committed or after 100000 transactions are committed. Given the low activity, the 1000 blocks threshold will be reached frequently, ensuring efficient performance despite frequent checkpoints.

Large Databases

For larger databases or higher user activity, use these settings:

checkpoint buffers = 10000       # Medium size checkpoint file
checkpoint transactions = 100000 # Unlikely to reach this limit

Explanation: These settings will result in less frequent checkpoints due to the higher block threshold, but the increased database activity will still ensure efficient performance.

Further Tuning

For even larger databases, consider increasing the checkpoint buffers value further:

checkpoint buffers = 50000       # Larger checkpoint file
checkpoint transactions = 100000 # Unlikely to reach this limit

Explanation: Testing different values can help you find the optimal configuration for your specific use case. Larger values for checkpoint buffers can lead to improved performance by reducing the frequency of checkpoints, but it’s important to monitor and adjust based on actual performance metrics.

Conclusion

By carefully adjusting the checkpoint buffers and checkpoint transactions settings, you can optimize Zim Server performance for both small and large databases. Regular monitoring and testing different configurations will help you achieve the best balance for your specific environment.

Maximum Data Blocks

This option specifies the number of data blocks that Zim Server will keep in shared memory simultaneously. It significantly impacts Zim Server efficiency by optimizing the number of input and output operations. The larger this option, the more efficient Zim Server will be. However, it requires a substantial amount of shared memory. If insufficient real memory is available, the operating system will start swapping, which can drastically reduce performance.

Maximum Databases

This option determines how many Zim databases will be processed concurrently. The default is 3, but reducing this number to the minimum necessary will decrease the amount of shared memory required.

Maximum Tables

This option indicates the number of Zim tables (entity sets and relationships with fields) that will be processed across all databases. Keeping this number as low as possible will minimize shared memory usage.

Maximum Users

This option sets the maximum number of users allowed to connect to Zim Server, up to the number of Zim licenses purchased. Reducing this number to the minimum needed will conserve shared memory.

Object Sleep, Object Timeout, Pending Sleep, and Pending Timeout

These parameters define the wait and timeout durations when attempting to acquire various Zim Server internal objects. Lower values result in faster reactions to resolve issues (usually by deadlocking), allowing other users to proceed. Use the suggested values in the configuration files below.

Scatter Table Entries

This option specifies the maximum sizes of transactions in blocks that all users connected to Zim Server can perform simultaneously. If there are 10 users connected but only 5 performing transactions, only these will count. For example, if the average number of blocks processed is 500, the number of entries used will be 2,500. Once a transaction is finished, all entries used in that transaction are released. This number cannot be smaller than Scatter Table Links. A good approach is to calculate 3 to 5 times that number.

Scatter Table Links

This option sets the maximum size for a transaction in blocks, allowing transactions to process different blocks of data up to this limit. For instance, an ADD statement creating a very large Zim file (e.g., 500 MB) will require this parameter to be at least 500,000. However, such commands are not common daily, suggesting a specific configuration for large operations. The larger this number, the more efficient Zim Server will be. A good reference is to multiply Maximum Data Blocks by two or three. This parameter cannot be smaller than Maximum Data Blocks.

Configuration Files

Small Size Database Configuration File

blocks per read = 8
buffers per user = 1000
checkpoint buffers = 1000
checkpoint transactions = 100000
datablock timeout = 1
files per transaction = 20
first file to reclaim = 100
maximum blocks per user = 2000
maximum data blocks = 20000
maximum databases = <number>
maximum file locks = 200
maximum locks = 10000
maximum record groups = 2000
maximum tables = <number>
maximum users = <number>
object sleep = 1
object timeout = 1
pending sleep = 5
pending timeout = 5
processors = 1
quick locks = 10
reclaim object size = 1000
record group size = 256
scatter table entries = 70000
scatter table links = 50000
scatter table size = 100
secondary lock group size = 20
secondary lock groups = 7500
server port number = 6002

Medium Size Database Configuration File

blocks per read = 8
buffers per user = 1000
checkpoint buffers = 10000
checkpoint transactions = 100000
datablock timeout = 1
files per transaction = 20
first file to reclaim = 100
maximum blocks per user = 2000
maximum data blocks = 50000
maximum databases = <number>
maximum file locks = 200
maximum locks = 10000
maximum record groups = 2000
maximum tables = <number>
maximum users = <number>
object sleep = 1
object timeout = 1
pending sleep = 5
pending timeout = 5
processors = 1
quick locks = 10
reclaim object size = 1000
record group size = 256
scatter table entries = 150000
scatter table links = 100000
scatter table size = 100
secondary lock group size = 20
secondary lock groups = 7500
server port number = 6002

Large Size Database Configuration File

blocks per read = 8
buffers per user = 1000
checkpoint buffers = 50000
checkpoint transactions = 100000
datablock timeout = 1
files per transaction = 20
first file to reclaim = 100
maximum blocks per user = 2000
maximum data blocks = 100000
maximum databases = <number>
maximum file locks = 200
maximum locks = 20000
maximum record groups = 4000
maximum tables = <number>
maximum users = <number>
object sleep = 1
object timeout = 1
pending sleep = 5
pending timeout = 5
processors = 1
quick locks = 10
reclaim object size = 1000
record group size = 256
scatter table entries = 800000
scatter table links = 250000
scatter table size = 100
secondary lock group size = 20
secondary lock groups = 7500
server port number = 6002

By carefully adjusting these settings, you can optimize Zim Server performance for different database sizes. Regular monitoring and testing different configurations will help you achieve the best balance for your specific environment.