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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL OneDB™ database servers.
Administrator's GuideThe HCL OneDB™ Administrator's Guide provides the information required to administer HCL OneDB™.
Disk, memory, and process management
Virtual processors and threadsThese topics describe virtual processors, explain how threads run within the virtual processors, and explain how the database server uses virtual processors and threads to improve performance.
Virtual processor classesEach class of virtual processor is dedicated to processing certain types of threads.
Disk I/O virtual processorsThe following classes of virtual processors perform disk I/O: PIO (physical-log I/O), LIO (logical-log I/O), AIO (asynchronous I/O), and CPU (kernel-asynchronous I/O).
I/O prioritiesThe database server prioritizes disk I/O by assigning different types of I/O to different classes of virtual processors and by assigning priorities to the nonlogging I/O queues.

I/O priorities

The database server prioritizes disk I/O by assigning different types of I/O to different classes of virtual processors and by assigning priorities to the nonlogging I/O queues.

Prioritizing ensures that a high-priority log I/O, for example, is never queued behind a write to a temporary file, which has a low priority. The database server prioritizes the different types of disk I/O that it performs, as the table shows.

Table 1. How database server prioritizes disk I/O
Priority	Type of I/O	VP class
1st	Logical-log I/O	CPU or LIO
2nd	Physical-log I/O	CPU or PIO
3rd	Database I/O	CPU or AIO
3rd	Page-cleaning I/O	CPU or AIO
3rd	Read-ahead I/O	CPU or AIO