Case:
I want to change my current RAID 1 setup with 2 harddrives to use 4 harddrives in probably a RAID-5 setup.
RAID 5:
One drive can go down without dataloss.
RAID 5. This RAID level also provides data redundancy, but it requires at least three disks. RAID 5 uses the capacity of one disk to protect you from data loss if one disk fails. Your data is distributed across multiple disks to improve disk performance. The total capacity of your storage system equals the capacity of all your disks minus the capacity of one disk. It is supported on systems with at least four drive bays.
To examine:
X-RAID vs Flex-RAID
…
Well, now I just add the 2 new harddrives… Lets see what happens.
Twenty minutes later: “I was getting impatient as nothing happened – but then – as I was about to try some stuff (like formatting / making a volume) I realized that the expansion was automatically started – and RAID 5 was automatically made! Nice! 🙂
Just some patience is needed. Currently ramaining time is … 49 hours!!! In my case, this means it will first be ready next year! Happy New Year soon!”
Logs:
| Wed Dec 31 2014 1:49:18 | Volume: Rebuilding started for Volume ‘data’. |
Anyway its probably better to read here: Expansion on ReadyNAS
Taken from http://kb.netgear.com/app/answers/detail/a_id/22802/related/1
What is X-RAID and how does it work with my ReadyNAS OS 6 storage system?
X-RAID is an auto-expandable RAID technology that is available only on ReadyNAS systems. With X-RAID, you do not need to know intricate details about RAID to administer your system. X-RAID allows you to add storage space without reformatting your drives or moving your data to another location. Because the expansion happens online, you can continue to use your ReadyNAS system while the volume capacity increases.
Because X-RAID is a single-volume architecture, if you configure your hard disk drives to use X-RAID, your storage system has only one volume that is made up of all installed hard disk drives. X-RAID’s single-volume architecture has two major advantages:
- Easy system management
- Auto-expansion
With Flex-RAID formatting, if you want to add disks to expand your storage capacity, you must back up the data to another system, add a disk, reformat the RAID volume, and restore the data to the new RAID volume. With X-RAID, none of those administrative tasks are required. Instead, with X-RAID, your volume automatically expands to accommodate additional disks or larger-capacity disks.
With X-RAID, you can start out with one hard disk, add a second disk for data protection, and add more disks for additional storage capacity. X-RAID accommodates the new disks automatically. You can replace existing disks with larger-capacity disks and X-RAID automatically accommodates the new disks.
X-RAID requires a minimum of two hard disks to provide protection against disk failure. If you have a one-disk ReadyNAS storage system and want protection from disk failure, you need to add a second disk that is at least as large as the first. It can be added while the system is running.
X-RAID uses the capacity of one disk for data storage and reserves the capacity of a second disk for data protection, which allows the volume to recreate data if a disk fails. In a two-disk system, the usable storage space is one disk. In a three-disk system, the usable storage space is two disks. In general, the total capacity of your storage system equals the capacity of all your disks minus the capacity of one disk.
The following figure illustrates how X-RAID uses new disks.
- The first disk that you install is used for initial (unprotected) storage space.
b. The second disk that you install is reserved for data protection (parity information).
c. Installing additional disks increases your storage space.Note: X-RAID reserves the capacity of one disk for data protection. The actual space reserved for data protection is distributed across all disks.
Note that although you can reuse the physical disk from another system to add capacity, any existing data on the disk must be removed before the disk can be added to the X-RAID volume. For more information about the reuse of disks see the following topics:
Taken from What is Flex-RAID and how does it work with my ReadyNAS OS 6 storage system?
What is Flex-RAID and how does it work with my ReadyNAS OS 6 storage system?
NETGEAR’s Flex-RAID technology allows you to choose from among several industry-standard RAID levels:
- JBOD. This most basic RAID level does not protect your data from loss if one of your drives fails. JBOD is available only on volumes consisting of a single hard disk.
- RAID 0. RAID 0 distributes data across multiple disks, resulting in improved disk performance compared to systems that do not use RAID formatting. The total capacity of your storage system equals the capacity of the smallest of your disk drives times the number of disks. RAID 0 is available on volumes consisting of two or more hard disks.
- RAID 1. This RAID level provides full redundancy of your data, because it duplicates data across multiple disks. Exactly the same data is stored on two disks at all times. RAID 1 protects your data from loss if one disk fails. The total capacity of our storage system equals the capacity of your smallest disk.
- RAID 5. This RAID level also provides data redundancy, but it requires at least three disks. RAID 5 uses the capacity of one disk to protect you from data loss if one disk fails. Your data is distributed across multiple disks to improve disk performance. The total capacity of your storage system equals the capacity of all your disks minus the capacity of one disk. It is supported on systems with at least four drive bays.
- RAID 6. This RAID level can recover from the loss of two disks. Your data is distributed across multiple disks to improve disk performance. The total capacity of your storage system equals the capacity of all your disks minus the capacity of two disks. It is supported on systems with at least four drive bays.
- RAID 10 (or 1+0). This RAID level uses both RAID 1 and RAID 0 technology. First, your data is duplicated so that exactly the same data is stored on two or more disks. Then, the data is distributed across additional disks to improve disk performance. It is supported on systems with at least four drive bays.
The Flex-RAID levels that you can select depend on the number of disks included in the volume. The following table describes the Flex-RAID levels that are available for a given number of disks. It also indicates whether adding a disk for data protection is possible for each configuration.
Flex-RAID levels and data protection
| Number of Disks per Volume | RAID Level | Can I add a disk for data protection? |
| 1 | JBOD | No. (JBOD is available only for volumes consisting of one disk) |
| 2 | RAID 1 | No. (Volume protection is already redundant.) |
| 2 or more | RAID 0 | No. (RAID 0 does not offer protection) |
| 3 or more | RAID 5 | Yes. (Additional disk provides dual redundancy and converts the volume to RAID 6.) |
| 4 or more (even number) | RAID 10 | No. (Volume protection is already redundant.) |
| 4 or more | RAID 6 | No. (Voume is already protected with dual redundancy.) |
For more information on changing RAID levels, see the ‘”How support article.
Published 03/28/2013 09:34 AM | Updated 11/27/2014 12:29 AM
jma73it 