On Wed, Jul 26, 2006 at 11:11:28PM -0400, Glenn Dekhayser wrote:
The most overused sentence: "It depends".
There's the WAFL RAID overhead; I've never gotten a real good feel for that but let's call it 5%- (anyone care to amend that?)
The RAID itself doesn't give any extra overhead beyond the parity disks.
WAFL of course has some overhead like any other filesystem depending on the number and size of files and directories.
In my experience (many small files about 11k on average, e.g. a html store) the prominent figure is the blocksize of 4K. The EMC NAS servers used 16k (i.e. significantly more waste). Solaris UFS used 8k but allows for 1k fragments (i.e. a bit more efficient than WAFL).
If you use it for large database files there is probably no significant difference.
Greetings,