ra_pages and io rate

Hi , When i strace the aio vps , no matter what the value i set for ra_pages , the pread system calls always request 2kb. disk blocks form the disk subsystem . How can i achive high io rates with informix. (For instance , in oracle by using db_file_multi_block_read_count , i can achive 1mb. per read.) Kind Regards, hope

hopehope_123 wrote: > Hi , > > When i strace the aio vps , no matter what the value i set for ra_pages > , the pread system calls always request 2kb. disk blocks form the disk > subsystem . How can i achive high io rates with informix. (For instance > , in oracle by using db_file_multi_block_read_count , i can achive 1mb. > per read.) Do NOT try to tune Informix like you would Oracle! Informix ALWAYS reads and writes either a single disk page (2 or 4K prior to IDS 10.00), performs a 'bigread' of 4 pages (8K or 16K), or does a block write of 4 pages at a time. Period. Are you having some performance problem? Post the symptoms and we'll suggest some onstat output and onconfig parameters we want to review for you. Don't forget to describe your system/environment including: Platform & OS (including version), IDS version (including fixpack level), type of disk farm (JBOD, RAID*, etc.) along with the symptom. If you are just trying to increase read-ahead efficiency, not to worry IDS is pretty efficient at it without help. 8-O Art S. Kagel