On Monday August 29, neilb@xxxxxxxxxxxxxxx wrote: > On Sunday August 28, tlg1466@xxxxxxxxxxxx wrote: > > I recently stumbled upon ddraid. Would this work at all for what I'm > > looking for? > > I'm not certain, but I suspect not. > Having reflected a bit more on what I learned at the linux.conf.au talk on the subject, I'm beginning to suspect "so" rather than "not". ddraid uses a modified raid3 algorithm. Each device block (which is typically 1 or 4 k) is split into individual (512byte) sectors and these striped over the physical devices. Thus every write is a full-stripe-write so no pre-reading is needed and there is no need for co-ordination with other blocks to calculate the parity. Because if this, multiple hosts could write to the array providing they agree beforehand who is allowed to write to which block - no further co-ordination is required. This co-ordination would be needed for dlvm or gfs anyway, so it is quite possible that it can be used in a very distributed way. However I've never actually used it, so I cannot promise anything. NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
