IBM PureData System for Analytics, Version 7.1
IBM PureData System for Analytics, Version 7.1
The segment size is the maximum amount of data that is written or read from a disk per operation before the next disk in the array is used.
Segment size can be different for different RAID types. There is no advantage in using a smaller segment size with RAID1. With high throughput workload, like in the case ofIBM® Netezza® Platform Development Software, the focus is on moving larger but fewer I/Os. In the high throughput environment, the stripe size must be equal to, or even a multiple of, the host I/O size.
The total of all the segments for one pass of all the back-end data disks is a stripe. Therefore, large segment sizes that can equal the I/O size, might be necessary to accomplish the higher throughput.
For RAID1 and host I/O size of 1 MB (VMFS block size), use large segments with size 256 KB or higher to get the most from each stripe.