What is RAID 10 and 01?

Question

I know about raid 0,1,,and 5. What is RAID 10 and 01 Combinations?

Answer 1

RAID 0+1 (also called RAID 01, not to be confused with RAID 1), is a RAID used for both replicating and sharing data among disks. The difference between RAID 0+1 and RAID 1+0 is the location of each RAID system — RAID 0+1 is a mirror of stripes. The size of a RAID 0+1 array can be calculated as follows where n is the number of drives (must be even) and c is the capacity of the smallest drive in the array:



A RAID 10, sometimes called RAID 1+0, or RAID 1&0, is similar to a RAID 0+1 with exception that the RAID levels used are reversed — RAID 10 is a stripe of mirrors.

All but one drive from each RAID 1 set could fail without damaging the data. However, if the failed drive is not replaced, the single working hard drive in the set then becomes a single point of failure for the entire array. If that single hard drive then fails, all data stored in the entire array is lost. As is the case with RAID 0+1, if a failed drive is not replaced in a RAID 10 configuration then a single uncorrectable media error occurring on the mirrored hard drive would result in data loss. Some RAID 10 vendors address this problem by supporting a "hot spare" drive, which automatically replaces and rebuilds a failed drive in the array.

Given these increasing risks with RAID 10, many business and mission critical enterprise environments are beginning to evaluate more fault tolerant RAID setups that add underlying disk parity. Among the most promising are hybrid approaches such as RAID 51 (mirroring above single parity) or RAID 61 (mirroring above dual parity).

RAID 10 is often the primary choice for high-load databases, because the lack of parity to calculate gives it faster write speeds.

RAID 10 Capacity: (Size of Smallest Drive) * (Number of Drives) / 2

The Linux kernel RAID10 implementation (from version 2.6.9 and onwards) is not nested. The mirroring and striping is done in one process. Only certain layouts are standard RAID 10 with the rest being proprietary. RAID 0+3

[RAID level 30 is also known as striping of dedicated parity arrays. It is a combination of RAID level 3 and RAID level 0. RAID 30 provides high data transfer rates, combined with high data reliability. RAID 30 is best implemented on two RAID 3 disk arrays with data striped across both disk arrays. RAID 30 breaks up data into smaller blocks, and then stripes the blocks of data to each RAID 3 raid set. RAID 3 breaks up data into smaller blocks, calculates parity by performing an Exclusive OR on the blocks, and then writes the blocks to all but one drive in the array. The parity bit created using the Exclusive OR is then written to the last drive in each RAID 3 array. The size of each block is determined by the stripe size parameter, which is set when the RAID is created.

One drive from each of the underlying RAID 3 sets can fail. Until the failed drives are replaced the other drives in the sets that suffered such a failure are a single point of failure for the entire RAID 30 array. In other words, if one of those drives fails, all data stored in the entire array is lost. The time spent in recovery (detecting and responding to a drive failure, and the rebuild process to the newly inserted drive) represents a period of vulnerability to the RAID set

A RAID 100, sometimes also called RAID 10+0, is a stripe of RAID 10s. RAID 100 is an example of plaid RAID, a RAID in which striped RAIDs are themselves striped together. Below is an example in which two sets of four 120 GB RAID 1 arrays are striped and re-striped to make 480 GB of total storage space

All but one drive from each RAID 1 set could fail without loss of data. However, the remaining disk from the RAID 1 becomes a single point of failure for the already degraded array. Often the top level stripe is done in software. Some vendors call the top level stripe a MetaLun (Logical Unit Number (LUN)), or a Soft Stripe.

The major benefits of RAID 100 (and plaid RAID in general) over single-level RAID are better random read performance and the mitigation of hotspot risk on the array. For these reasons, RAID 100 is often the best choice for very large databases, where the underlying array software limits the amount of physical disks allowed in each standard array. Implementing nested RAID levels allows virtually limitless spindle counts in a single logical volume.

RAID 50 combines the straight block-level striping of RAID 0 with the distributed parity of RAID 5. This is a RAID 0 array striped across RAID 5 elements.


One drive from each of the RAID 5 sets could fail without loss of data. However, if the failed drive is not replaced, the remaining drives in that set then become a single point of failure for the entire array. If one of those drives fails, all data stored in the entire array is lost. The time spent in recovery (detecting and responding to a drive failure, and the rebuild process to the newly inserted drive) represents a period of vulnerability to the RAID set.

The configuration of the RAID sets will impact the overall fault tolerance. A construction of three seven-drive RAID 5 sets has higher capacity and storage efficiency, but can only tolerate three maximum potential drive failures. Because the reliability of the system depends on quick replacement of the bad drive so the array can rebuild, it is common to construct three six-drive RAID5 sets each with a hot spare that can immediately start rebuilding the array on failure. This does not address the issue that the array is put under maximum strain reading every bit to rebuild the array precisely at the time when it is most vulnerable. A construction of seven three-drive RAID 5 sets can handle as many as seven drive failures but has lower capacity and storage efficiency.

RAID 50 improves upon the performance of RAID 5 particularly during writes, and provides better fault tolerance than a single RAID level does. This level is recommended for applications that require high fault tolerance, capacity and random positioning performance.

As the number of drives in a RAID set increases, and the capacity of the drives increase, this impacts the fault-recovery time correspondingly as the interval for rebuilding the RAID set increases.

A RAID 60 combines the straight block-level striping of RAID 0 with the distributed double parity of RAID 6. That is, a RAID 0 array striped across RAID 6 elements.It requires at least 8 disks.

Answer 2

they are actually 0+1 and 1+0.
0+1: stripe a set of disks then mirror them to another stripe.
1+0: Mirror first, then stripe
Here is a pretty good site:
http://www.acnc.com/04_01_00.html

Answer 3

Go to Wikipedia and search for: Raid array

All will be revealed.

Answer 4

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