I apologze for being unclear. As I did comparisons between software and hardware raid, one of the advantage s that I noticed with hardware raid was cache (both read and write). With hard ware it is usually larger giving some increase in performance. I was looking for a way to allocate more system memory specifically to be the md cache area to give that extra feature of that hardware raid. This would especially be ben efitial for a NAS that has a dedicated purpose to fast reliable storage. Thanks for your time. Brian Pontius -----Original Message----- From: Neil Brown <neilb@xxxxxxxxxxxxxxx> Sent: Jun 2, 2004 10:10 PM To: Brian Pontius <linuxboy123@xxxxxxxxxxxxxx> Cc: linux-raid@xxxxxxxxxxxxxxx Subject: Re: Md cache? On Wednesday June 2, linuxboy123@xxxxxxxxxxxxxx wrote: > to all, > > Is anyone aware of a way to cause the md devices to use some system memory as a write cache? (maybe through mdadm?). I have looked everywhere and cannot seem to find anything about such a feature. > > If not, anyone know if this is a possibility for the future, Neil? What is it exactly that you want. All device IO is cached in memory before being written to the device. The only real value of a cache with a RAID array is if it we a non-volatile cache. Is that what you were thinking of. 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
