The allocation block size (also known as cluster size or bytes per cluser) is a "block" of data on a drive. Depending on the size of a block, it can take one or many blocks per file and the number of blocks taken is the size taken on the drive. On some of our servers we have the block size set to 32KB for multiple reasons, but for the most part it is set for the performance of the drive and requirements of the size of RAID setups we have. By default, our RAID setups want to have 64KB block sizes, however, we set the block size to 32KB for space usage as well as our backup system supports a max of 32KB block sizes at this time.

Due to the block size, you may notice a difference in the quota on the server and what you uploaded. The quota is returned to us by the operating system and is the space being taken up on the server.

We believe that the performance of a server is very important and so have used a block size that will give the best IO (input/output) on our RAID setups as well as our backup sysstem will support.