Below is a list of terminology used in this paper:

Term:

Definition:

Column

Columns correlate to underlying physical disks across which one stripe of data for a storage space is written. Typically the column count will be equal to the number of physical disks of the storage space (for simple spaces) or half of the number of disks (for mirror spaces). The column count can be lower than the number of physical disks but never higher.


Interleave

Interleave represents the amount of data written to a single column per stripe.


Block Size

Block size is a measure of how large or small, in kilobytes or megabytes a read or write request is. This is one of the most important parameters of a workload.


Outstanding I/Os

Also referred to as “Queue Depth”, outstanding I/Os measures how many read or write requests are queued up to be serviced by a disk, Space or other device.





Ref: http://social.technet.microsoft.com/wiki/contents/articles/15200.storage-spaces-designing-for-performance.aspx