Compaq ProLiant 1000 Configuration and Tuning of Sybase System 11 for NetWare - Page 18

Page 14 Configuration and Tuning of Sybase System 11 for NetWare on Compaq Servers measured rates of up to 90 random I/Os per second per drive, some of which were being temporarily cached by the Array Accelerator. Checking Disk I/O Rate Try not to overload any individual disk with random I/Os. To determine the I/O rate per drive, first determine the number of I/O's per second to each logical volume. The Novell Monitor utility reports on the number of concurrent disk requests that are queued but doesn't tell you on which database device the I/O is occurring on. The Sybase SQL Monitor utility can determine the I/O rate per database device. It is best to use values from the SQL Monitor averaged over a period of time to calculate I/O rates. Using the above output as an example, the calculations for determining the number of sequential writes to the transaction log device are relatively simple. The transaction log is located on a single logical volume consisting of 2 2.1GB drives attached to the SMART-2 Array Controller. The log volume is using RAID1 for fault tolerance. From Sybase SQL Monitor the log device shows zero reads and 94 writes. Log device I/O: (0 reads + (94 writes * 2 writes per volume for RAID1)) = 188 writes per volume / 2 drives per volume = 94 writes per drive < 160 maximum sequential writes per 2.1GB drive Now lets calculate the I/O rate for the data devices. The data devices are located on single logical volume consisting of 14 2.1GB drives attached to a second SMART-2 Array Controller. The volume is using RAID5 for fault tolerance. Sybase SQL Monitor show the following I/O device rates for the data devices: acct1: 42 reads + 28 writes © 1996 Compaq Computer Corporation, All Rights Reserved Doc No 140A/0896