| Article Index |
|---|
| RAID 101 - Introduction to RAID |
| RAID 0 - Striping |
| RAID 1 - Mirroring |
| RAID 3 - Striping with Dedicated Parity |
| RAID 5 - Striping with Distributed Parity |
| Wrap-Up |
| All Pages |
Page 6 of 6
RAID 101 - Wrap Up
We hope you've enjoyed RAID 101 - Introduction to RAID. We've covered the 4 basic RAID types:
| RAID Level |
Name |
Redundancy |
Great For |
Not Great For |
| RAID 0 |
Striping |
None |
Temporary files |
Data you want to protect |
| RAID 1 |
Mirroring | Yes - 1 Disk |
Operating Systems Database Logs |
Data sets bigger than one disk Large amounts of cheap storage |
| RAID 3 |
Striping with Dedicated Parity |
Yes - 1 Disk |
Large Data Sets that are mostly read from |
Data Sets that are mostly written to |
| RAID 5 |
Striping with Distributed Parity |
Yes - 1 Disk |
Large Data Sets |
Data sets with many small random disk writes |
So what if your data doesn't fit these models? What if you need to survive the simultaneous failure of 2 disks, or handle lots of small random writes? What if you have a system that uses the disks very heavily and you need high performance? We'll look at solutions for these systems in RAID 201 - Advanced RAID Levels I and RAID 202 - Advanced RAID Levels II.
Comments (4)
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|192.101.136.xxx |2009-05-28 06:46:55 doublemint - homebuilt NAS ownerI'd also like to know what the recovery process is like, especially if the RAID controller fails. Can a failed RAID controller be replaced with one of a different brand and still recover? As a novice, the RAID BIOS is a bit confusing, some pointers would be helpful. I had a motherboard with RAID fail and assumed I could take one of my RAID 1 drives, plug it into another PC and read it however I couldn’t, why?
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|70.17.178.xxx |2009-05-28 13:53:44 zaphod - replyIm pretty sure youd need both HDs for that to work... not just one.
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|134.211.129.xxx |2009-05-29 17:13:22 David Rawling - Your Mileage Will VaryBasically, the answer is no - you need the same model of RAID controller to replace a failed one.
This applies from the virtually-free Intel RAID controllers on the motherboard to the thousand (and multiple-thousand) dollar add-in cards.
Each controller has its own way of marking the disks as being part of a RAID set - the disk "signature". One brand might write "RAID1-1" to the first disk and "RAID1-2" to the second. Others might use numbers with the brand (MYRAID-716825).
I guess it comes back to the same comment I made before. RAID is not backup. It only protects you from disk failure.
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|71.198.81.xxx |2009-06-01 02:54:12 doublemint - homebuilt NAS ownerDavid,
While unfortunate there isn't more standardization, I understand why this might be. I can't however understand why this would apply to RAID 1 (mirroring). Why do these drives need to be treated any different than non-RAID drives? Just write the same data two places rather than just one.
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