eG Monitoring
 

Measures reported by SybTxLogTest

This test reports statistics pertaining to the transaction logs of a Sybase database server. The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Ulc_log_writes The rate at which log records per transaction are written into the ULCs Records/Sec If this data is unusual, study the Max_ulc_size measure and look at your application for long-running transactions and for transactions that modify a large number of rows.
Ulc_log_write_waits The rate at which attempts made to write to ULCs encountered semaphore contention Waits/Sec  
Ulc_flushes The rate at which user log caches (ULCs) were flushed to a transaction log Flushes/sec The detailed diagnosis for this measure provides the percentage of ULC flushes due to full ULC, end transaction,change of database,system log record and other reasons.
Ulc_flush_waits The rate at which attempts made to flush ULC pages to the log encountered log semaphore contention Waits/Sec If this value is high, reduce the semaphore contention by:
  • Increasing the ULC size, if filling user log caches is a frequent cause of user log cache flushes
  • Reducing log activity through transaction redesign. Aim for more batching with less frequent commits. Be sure to monitor lock contention as part of the transaction redesign.
  • Reducing the number of multidatabase transactions, since each change of database context requires a log write.
  • Dividing the database into more than one database so that there are multiple logs. If you choose this solution, divide the database in such a way that multidatabase transactions are minimized.
Max_ulc_size The maximum number of bytes used in any ULCs, across all ULCs. This data can help you determine if ULC size is correctly configured. KB If this value is consistently less than the defined value for the user log cache size configuration parameter, reduce the user log cache size to Max_ulc_size value.
Log_allocations The rate at which additional pages were allocated to the transaction log Allocations/Sec This data is useful for comparing to other data in this test and for tracking the rate of transaction log growth.
Transaction_log_writes The rate at which the Adaptive server wrote a transaction log page to disk Pages/Sec  
Avg_writes_per_logpage The average number of times each log page was written to disk Writes/Page In high throughput applications, this number should be as low as possible.