I just got a rocketraid 1640 w/ 4 80g sata wester dig. I am going to be setting up raid 10. Looking through the instructions I see that it will at some poing ask me two questions that I am just not sure of. 1. Block size - I have a serveral choices between the ranges of 16 and 2048. I have no idea what I should be picking. I will be running FreeBSD, should the block size that I select here, match the block size that my file system is using.?? 2. Device mode - Im completely lost here... my choices are the following - PIO x - (choice between 0 through 4) MW DMAx - (choice between 0 through 2) ATA/x 0 - (Chioces are : 16, 25, 33, 44, and 66)
For reference: A RAID-10 is essentially the same thing as a RAID-0+1 (it just sounds catchier). Typically, you choose block size depending on the average filesize you will be working with. The norm is 64-128. If your system will be working with nothing but huge files regularly, you will want a larger than normal block size (1024-2048), and if you routinely work with tiny or fragmented files, you'll benefit from a smaller block size (16-32). PIO shouldn't be used unless the HDD's don't support DMA, in which case you'd want the highest possible value. DMA and ATA should be set to the highest allowable values.
ah its been a while since i looked at this post. Good stuff! i always tried to ignore the PIO crap. I imagine the lower the block size i use, the more inodes i get.. Since this will be handling mail, im gonna go with a fairly small block size... But on the other hand it will be doing more then just mail, and therefore my have a single file tha takes up a whole pile of inodes..... hmm.. I thnk ill go with something around 128-256... not sure yet.
