RAID 1+0 versus RAID 0+1

I am in the process of setting up a new server I need to know is it better to use RAID 1+0 for data with RAID 5 for logs and backups or RAID 0+1 for data with RAID 5 for logs and backups this is a hardware raid / storage system I am going to have lots of (24 x 7) daily data loads reads will be minimal right now but should have a consistent amount of reads/writes later down the road for OLTP processing fair amount of report processing done weekly and monthly thanks in advance

NO RAID5 NO RAID5 NO RAID5 NO RAID5 NO RAID5 NO RAID5 NO RAID5 wildpony wrote: > > I am in the process of setting up a new server > I need to know is it better to use RAID 1+0 for data with RAID 5 for > logs and backups > or RAID 0+1 for data with RAID 5 for logs and backups > this is a hardware raid / storage system RAID10 for data and RAID1 or (sparate) RAID10 for logs and rootdb. Backups can go anywhere since they should be swept to tape immediately or at least frequently if written to disk. If you do not sweep them immediately consider rcp'ing them to another system on the network immediately for safety. > I am going to have lots of (24 x 7) daily data loads > reads will be minimal right now but should have a consistent amount of > reads/writes later down the road for OLTP processing > fair amount of report processing done weekly and monthly Considering that write performance of RAID5 is 50% that of RAID0, RAID3 or RAID4 and that RAID10 does a bit better than straight RAID0 why even consider RAID5 for the MOST I/O intensive part of the server, the logical and physical (at least in 7.xx) log dbspaces? One could make the case that the RAID5 safety issue is moot for the logs since the physical log is transitory and the logical logs are constantly backed up (you are using one of the constant log backup options I hope) for a server with a low transaction rate, since write performance is not an issue either, but you are describing a server with an very high transaction rate initially and even down the road! Logical log write performance is CRITICAL to server performance in such a system! Art S. Kagel RAID10 RAID10 RAID10 RAID10 RAID10 RAID10 RAID10 RAID10

Art thank you..i have been trying to pound raid 10 into the sys admins head but i needed a few documented users opinions, but i guess all is at a deaf ear seeing that my hardware raid company can only do raid 5 or raid 01 so i guess i am just going to have to go with the raid 0+1 thanks very much for your input

wildpony wrote: > > Art > thank you..i have been trying to pound raid 10 into the sys admins head > but i needed a few documented users opinions, > but i guess all is at a deaf ear seeing that my hardware raid company can only > do raid 5 or raid 01 so i guess i am just going to have to go with the raid 0+1 Check with the vendor's internals guys. They may call it RAID01 but really be doing RAID10. The terminology is only hardening up in the last 2 years since I started pounding the net to get a sane definition of the two options. The key question to ask is "Can it rebuild just one drive if a drive fails or is the entire stripe copied to the other side of the mirror?" If yes, follow that with "So if another drive on the other side of the mirror fails before the rebuild completes, do I loose everything?" If the answers to these are "Yes" and "No" they are really doing RAID10 or some hybrid such that it does not matter. Art S. Kagel