What is mean by raid and types of raid level

[M.sureshkumar]

I need documents for What is mean by raid and types of raid level and hardware raid and software raid.

[Marco Santerre]

You may want to look in to this :

http://www.docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/5187-2216/5187-2216_top.html&con=/hpux/onlinedocs/5187-2216/00/01/105-con.html&toc=/hpux/onlinedocs/5187-2216/00/01/105-toc.html&searchterms=raid&queryid=20031127-062429

[Stefan Farrelly]

http://www.docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B2355-90742/B2355-90742_top.html&con=/hpux/onlinedocs/B2355-90742/00/00/98-con.html&toc=/hpux/onlinedocs/B2355-90742/00/00/98-toc.html&searchterms=levels%7craid&queryid=20031127-062506

or do to www.docs.hp.com and type into the search box "raid levels"

[Fabio Ettore]

Hi,

beginning from definition of RAID:

http://www.webopedia.com/TERM/R/RAID.html

and then very useful links to know all RAID arguments.

I hope this helps you.

Best regards,
Ettore

[Geoff Wild]

RAID - Redundant Array of Independent Disks

RAID 0 arrays are used where data transfer rate is the primary factor, safety is not a factor, and most data is sequential.

RAID level 1 is only data redundancy, which is obtained by disk mirroring or duplexing as it is also known.

RAID level 2 and 3 fall under a broad classification of parallel access arrays. RAID 2, however, utilizes an error correction type of algorithm that is often used in memory chips, known as Hamming code.

RAID level 3 is the most supported fault tolerant RAID class to be used with nonlinear editing systems, because in general it offers the next highest level of data throughput on both reading and writing to and from the hard disk array. RAID level 3 uses byte striping of data and is optimized for high data transfer rates, unlike RAID 4 and 5 which are optimized for transaction processing and small file transfers.

RAID 4 is considered an independent access array and not a parallel access array, so it is a better choice than RAID 3 for Fibre Channel. RAID 4 also requires the use of a dedicated parity disk like in RAID 3, but unlike RAID 3 it does not require synchronized hard drive spindles.

RAID 5 is probably the most common implementation of RAID on business servers, because of its fault tolerance and cost effectiveness over RAID 1, 3, or 4. RAID 5 splits the parity information across all the hard drives in the array, which increases the percentage of each hard drive that is available for user data.

RAID level 6 is even more fault tolerant than RAID 5, but is also slower than even RAID 5 in disk writes.

You can also have RAID 10 or sometimes called RAID 1+0 - mirroring with striping.

Rgds...Geoff

[Stuart Browne]

I always thought I in RAID was for 'inexpensive'.. I guess it depends on whos manual you read.

I've not heard of RAID 6 before though, but assume it's what HP's PC NetRAID controllers are calling 'ADG' ? (4 disk minimum, dual-parity striping, can cope with 2 failures within an array before chaos).

[Karthik S S]

Nice Docs,

http://www.storagereview.com/guide2000/ref/hdd/perf/raid/concepts/gen.html

hp-ux specific,
http://www.introcomp.co.uk/hpux/ --- Logical volume manager

Linux specific,
http://www.tldp.org/HOWTO/Software-RAID-HOWTO.html

-Karthik S S