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View Full Version : Raid 1, Raid 5, Stripe sets with Parity


Tahna Los
04-09-2001, 11:24 AM
Hi all.

To start off, I am a member of Charles Capps forum, the Solareclipse network.[nbsp][nbsp]I've been lurking here for quite some time now, as it is a VERY interesting place.[nbsp][nbsp]I hope to perhaps someday set up an account with you guys.[nbsp][nbsp]Or perhaps work for ya.[nbsp][nbsp]Either will do just nicely. :)

I am however, taking a course on networking, and I was wondering if it was okay to ask TeRRa some questions, *waves to TeRRa* Hi, can you see me?

We've just started doing stuff on Fault Tolerance.[nbsp][nbsp]I've seen TeRRa mumble on about Mirror sets and arrays (partition x got kicked out of the mirror array and I have to rebuild them... yadda yadda yadda).[nbsp][nbsp]Now I've learned that Mirror sets mirror the root hard drive so in case of failure of the primary partition, the secondary takes over.[nbsp][nbsp]The same applies to vice versa.

We've also learned about Stripe Sets with Parity (SSPs), where a stripe set is when data is spread over a set of 3 or more partitions and a parity set is used in the event of partition failure to reconstruct data.

Questions:
1) It appears that Mirror sets appear to be the better form of Fault Tolerance IMHO.[nbsp][nbsp]But why is Mirror Sets classified as RAID level 1 while Stripe Sets with Parity labelled as RAID level 5?
2) How is it possible to regenerate data in a SSP?[nbsp][nbsp]And why is it so much better than using Mirror Sets?
3) What kind of Fault Tolerance does FQ use?[nbsp][nbsp]How many mirrors do each Server have?[nbsp][nbsp]Do each server contain a Stripe set as well?[nbsp][nbsp]How many disks are used in these Stripe sets.
4) How big are the HDs in each server?

More questions to come.[nbsp][nbsp]Thanks to whomever could reply!!! :)
[This message has been edited by Tahna Los (edited 04-09-01@10:31 am)]

ryount
04-10-2001, 11:46 PM
I'll take a quick stab at this.[nbsp][nbsp]The problem with RAID1 can be cost.

For example, at my office our SQL server has 2x9GB as RAID1 for the OS and 3x18GB setup as RAID5 for the data.[nbsp][nbsp]This gives us 36GB of space in the RAID5 array since it costs you 1 drive to use RAID5.[nbsp][nbsp]We also have another 18GB as a hot swapable spare.[nbsp][nbsp]

If we used RAID1 for the data we would need 3 x 36GB drives for the same amount of space (2x36GB for RAID1 plus the spare).[nbsp][nbsp]RAID5 really starts to pay off in larger environments.[nbsp][nbsp]If I needed more space, I could have added another 18GB drive to the array and bring my storage to 54GB.

Check out www.adaptec.com (http://www.adaptec.com) for RAID info.[nbsp][nbsp]I seem to remember they had some good explanations there.