jwcolby
jwcolby at colbyconsulting.com
Fri Jun 25 08:00:18 CDT 2010
Most people are in agreement that reads are virtually full speed, or at least there are no parity calcs going on. The whole point really is that to really get any speeds out of raid, a hardware controller helps immensely. I decided to bite the bullet and spend the bucks for the Areca line, even though they are more expensive than the competition, and I have not been disappointed. The smaller controllers (up to 8 drive) have a fixed 256 megs of cache, soldered right on the board. I have one of those, my first purchase. I later purchased an "open box" 16 drive controller and it has a dimm socket, which I populated with the maximum 2 gigs of ram. In any case, you are at the mercy of the manufacturer as to implementation. In most cases software raid, using the motherboard chipset and software run by the operating system, are VERY slow on writes, though the reads are pretty good. Where the hardware co-processors can help is turning the raid into an orchestra. These guys come to know RAID and how to do it right. I chose Areca based on reviews in the magazines that consistently placed them way above the competition. I don't have the links any more but the numbers were not just a small percentage faster. Anyway, back when I was trying to figure out how to do this I read the reviews and made a decision based on the numbers that Raid6, at least as implemented by Areca, was a valid storage option. John W. Colby www.ColbyConsulting.com Drew Wutka wrote: > Great article, thanks for the link John. There is one issue with the > technical details. The 'reading' is on paper like that, but most real > life RAID 5's are slower on read then the same drives in a raid 0,10 or > 0+1. (Probably due to the overhead of the parity being checked...would > depend on the operation of the actual controller.) > > Drew > > -----Original Message----- > From: accessd-bounces at databaseadvisors.com > [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of jwcolby > Sent: Thursday, June 24, 2010 9:44 PM > To: Access Developers discussion and problem solving > Subject: [AccessD] Storage Advisors > Blog Archive > Yet another RAID-10 > vs RAID-5 question > > This for Drew... > > http://storageadvisors.adaptec.com/2007/04/17/yet-another-raid-10-vs-rai > d-5-question/