RAID5 Frequently Asked Questions

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Various Questions

RAID 5 Characteristics

How will a system performance change if I create a RAID5 on my disks?

There are two possibilities:

  • frequently used files and folders are on the array;
  • your rarely used data stored on the array (e.g. the RAID 5 array is used as a backup).

In the first case, overall system performance increases as compared to a single disk, because read speed increases. Write speed doesn't change.

In the second case, you hardly notice any performance changes.

How to make a RAID 5 bootable?

If RAID 5 was created using software (an operating system driver), then it is impossible to make such a RAID 5 bootable. In case of a hardware RAID 5, you can install operating system on one of the array volumes, and then set BIOS to boot from the array.

What is the minimum of member disks required to build a RAID5 array?

The minimum of three disks is required to create a RAID 5.

What is overhead and how big is it in RAID5?

Overhead in a fault tolerant storage system is resources expended to provide a redundancy and fault tolerance rather than for storing user data. Overhead exists in many aspects of storage system such as:

  • disk space;
  • access speed (IOPS values);
  • a number of hardware parts (disks and ports).

Usually when we talk about a RAID we mean a disk space overhead, while performance is considered separately. RAID 5 disk space overhead is one hard disk, regardless of the number of disks in the array.

See also

Useful links

About RAW File System

Unerase Software Comparison

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