February 6, 2003 at 8:50 am
I would like to get some opinions and feedback regarding "Advanced Data Guarding" as a RAID solution for SQL data. The data will be stored and accessed from a Direct Attached Storage unit using 6 x 36GB HDD's. I have not found a lot of information on this solution as of yet.
February 6, 2003 at 10:08 am
What is advanced data guarding? Is this RAID5? 1+0?
Sounds like a vendor term.
Steve Jones
February 6, 2003 at 11:33 am
Yes. ADG is vendor specific technology from Compaq and Smart Array 5300 Controllers. Definition-Advanced Data Guarding: Two sets of parity data distributed across all drives. Protects against the failure of any two drives in an array. Provides high fault tolerance at a minimum implementation cost.
February 6, 2003 at 2:00 pm
Like Raid 5 +.
Here's the FAQ:http://h18004.www1.hp.com/products/servers/proliantstorage/arraycontrollers/adg/questionanswer.html
Looks like the space usage for parity is 2 drives and is worth it above 5 drives. Basically appears to be items.
1. Allows 2 drives to fail (nice)
2. Allows up to 56 drives, RAID 5 is for 14 drives or less.
The 2 drive failures is nice, htough at PASS some analysis showed that above 8 drives, the efficiency gains aren't great. Might want to look at another array above that rather than addnig more drives.
What application are you thinking of? How big is the db?
Steve Jones
February 6, 2003 at 2:08 pm
It's an inhouse web app being converted from a menu driven app currently on VMS. Expect DB to be around 50GB to start.
February 6, 2003 at 4:44 pm
Interesting idea. Whats the difference between this and just running a hot spare? No performance lag while the spare gets up to speed?
Andy
February 6, 2003 at 5:46 pm
Probably that's it. Covers two drives failing before the spare gets going.
If you get it for no $$, might as well. Buy 5-8 drives for your main array, 2 more for logs, 2 more for OS and should be golden.
Steve Jones
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