RAID0 or RAID5

[Caster Troy]

If there are 3 Hard Disks of 146.8GB what are the advantages of configuring them with RAID5 and what are the advantages of configuring 3 seperate RAID0 volumes OR extending 1 RAID0 volume.

[David Claypool]

RAID 0 = striping; high performance with no redundancy; utilizes the entire capacity of the drives
RAID 1 = mirroring; redundancy with a slight performance hit; ; requires 100% more disk than is used
RAID 1+0 = mirroring+striping; redundancy with no performance hit; ; requires 100% more disk than is used
RAID 5 = distributed parity; redundancy with a larger performance hit; ; requires 50% more disk than is used

You basically have 3 options with 3 drives and an HP SmartArray controller:

RAID 0 (striped across all 3 drives with 440GB of usable storage)
RAID 1+0 with an online spare (mirrored and striped with 146GB of usable storage; in the event of disk failure the 3rd drive will be automatically substituted for the failed drive, protecting against an additional failure which would be non-recoverable)
RAID 5 (distributed across all 3 drives with parity and 292GB of usable storage; in the event of a failure of a disk there is no protection against additional disk failures until it is replaced)

If you're serving a lot of data that is static and originates somewhere else and performance isn't an issue, RAID 0 would be a good choice for you. However, you must keep in mind that any disk failure will be catastrophic because you have no redundancy.

If you're operating in a critical environment and need to make sure the application is always available, RAID 1+0 with an online spare is your best option.

If you're serving a fair amount of data and performance isn't an issue, RAID 5 would be a good choice for you.

[Shameer.V.A]

Hi Javed,
Happy New Year.

RAID 0 = striping; high performance on both Read & Write operations. as data is striped between disks data can read/write parallely,but with no redundancy, one disk failure can lead to total data loss; utilizes the entire capacity of the drives - only recommended for archived data storage purpose. ( if you 2*300Gb , wou will get full 600Gb effective)


RAID 1 = mirroring; maximum redundancy with a slight performance hit on Write operation; Read performance is normal, as data can be read from any one disk.
Requires 100% more disk than is used. ( if you 2*300Gb , wou will only get 300Gb effective)


RAID 1+0 = mirroring of 2 striped volumes; redundancy with least performance hit . Maximum Read Performance, slight performance hit on Write - as data has to be written to 2 volumes; ; requires 100% more disk than is used ( if you 4*300Gb , wou will only get 600Gb effective)

RAID 5 = distributed parity through block level ; redundancy with a larger performance hit- because of generating parity ; requires approx 33% more disk than required ( n-1 is the effective usable capacity, where n is the no. of disks).

Performance can be increased by spreading disks to multiple channel of RAID Controller & increasing RAID Controller CPU speed & Cache Memory. You can enable read ahead & Write back feature of RAID Controller, if you have BBU ( Battery Backup Unit) on RAID Controller.

Hope this will help you to choose the optimal configuration for site.

Shameer

[Joseph Loo]

hi,

a good reference material to decide on the RAID level u require:

http://www.acnc.com/04_00.html

regards.

[Caster Troy]

Thanx All, Finally I decided to configure 3 seperate RAID0 volumes for all 3 hard disks. Anyways thanx for ur timely help

[Caster Troy]

see my last reply