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RAID0 or RAID5

Caster Troy
Regular Advisor

RAID0 or RAID5

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.
Evil Has Its Winning Ways
5 REPLIES
David Claypool
Honored Contributor

Re: RAID0 or RAID5

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
Respected Contributor

Re: RAID0 or RAID5

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


.... See invisible, feel intangible and achieve impossible as everything is possible ....
Joseph Loo
Honored Contributor

Re: RAID0 or RAID5

hi,

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

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

regards.
what you do not see does not mean you should not believe
Caster Troy
Regular Advisor

Re: RAID0 or RAID5

Thanx All, Finally I decided to configure 3 seperate RAID0 volumes for all 3 hard disks. Anyways thanx for ur timely help
Evil Has Its Winning Ways
Caster Troy
Regular Advisor

Re: RAID0 or RAID5

see my last reply
Evil Has Its Winning Ways