Block Size vs. Stripe Size
It??™s common to confuse the terms block size and stripe size. Be clear and always use the
proper term:
??? Block size: Refers to how the disk storage physically stores information, and more
specifically to the smallest number of bytes read or written at one time. When a
disk partition (a drive letter) is formatted, it is created with a certain block size
(see Figure 10-1). The default block size is 512 bytes. Considering that SQL Server
writes data in 8K blocks, 16 reads or writes are required to transfer data for one
SQL Server block. It is possible to change that block size, but only when creating
the partition.
Figure 10-1. Disk-partition block sizes
??? Stripe size: Applies specifically to certain methods of disk configuration where a
parity stripe is written to provide redundancy (I??™ll cover these types of configurations
shortly). Many hardware controllers are hard-coded to a specific stripe size,
giving the impression that the block size configured for the disk itself isn??™t relevant.
CHAPTER 10 n HARDWARE CONSIDERATIONS 245
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