Knowledgebase
Could I mix hard disks in a RAID volume?
Posted by - NA - on 11 February 2011 15:39
We would recommend user using the same brand & model in a RAID.

At first, the different model might have a little dirrerence, for example, thought the same "1TB" disks, in A model, it might be 931GB (*1), in B model, it might be actually 930GB.

Case. 1

A new RAID-5 has three A disks, the capacity for the total RAID volume size will be 2*931GB.
When a disk fail and the user want to rebuild the RAID with a new B model, it will fail due to the actual size of B is small then A.

Case. 2

A new RAID-5 mixed up two A disks and one B disk, the capacity for the total RAID volume size will be 2*930GB.
When a disk fail and the user want to rebuild the RAID with a new A model or B model, it would be okay due due to the actual size of A is larger than B.

Before you replace a different disk, the "size" is very important.

Secondary, we won't recommend user mixing up different disks from different brand. Due to the performance, specification, access time, specifically some disks are not designed with RAID-specific.

Third, We strongly recommend using enterprise-class hard drives. In the hard drive manufacturer's web site, we also found that hard disk's manufacturers do not recommend using low power desktop models for RAID or NAS. For example: WD official Datasheet (http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-701229.pdf)

- Business Critical RAID Environments – WD Caviar Green Hard Drives are not recommended for and are not warranted for use in RAID environments utilizing Enterprise HBAs and/or expanders and in multi-bay chassis, as they are not designed for, nor tested in, these specific types of RAID applications. For all Business Critical RAID applications, please consider WD's Enterprise Hard Drives that are specifically designed with RAID-specific, time-limited error recovery (TLER), are tested extensively in 24x7 RAID applications, and include features like enhanced RAFF technology and thermal extended burn-in testing.keywo


*1. Please refer to I have 1TB disk, but the system tell me it was 931GB disk? (http://esupport.thecus.com/support/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=167)
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