What's the difference between raid 0 and raid1 HD?

[dusk]

Anyone one know if there any significance difference between them?

 

[Guest]

There is a BIG difference:

RAID 0 (known as "striping") basically links each drive in the array as one huge drive. Storage capacity is determined by the smallest drive in the array. That capacity is then applied to format all other drives in the array. If using a 4GB, 6GB, 5GB drive in a RAID 0 array, your system will see one huge drive of 12GB (4GB x 3) versus 15GB. RAID 0 offers double or more performance under sustained data transfers when one drive per IDE port is used. In such a configuration, unlike SCSI, IDE drives are always available to the system. SCSI requires more management of the SCSI bus.

RAID 1 (known as "mirroring") makes and maintains an identical image of data from one drive to a second drive or from multiple drives to a second set of multiple drives. Should one drive fail, the working drive or drive set continues operating. To the system, such an array is still seen as a single drive letter. While RAID 1 is the least efficient use of hard drives to provide data protection (since the user does not see any of the additional storage capacity of the mirrored drives), low-cost IDE makes it acceptable. If performing 1-to-1 mirroring with two 4GB drives, the system only sees one 4GB drive. IDE RAID 1 represents a significantly lower cost than SCSI RAID 1.



Lars Coleman
http://home.earthlink.net/~larscoleman

 

[dusk]

Thanks for the explainaition but i'm still not too clear. Do you know what raid do typical harddrive use? I want to buy the IBM deskstar 46gb 7200 rpm ata/100 but it show as raid 0,1. What's the meanning of that, does it run normally like other HD or something I should consider of? Pls advice

 

[Guest]

RAID Arrays are not determined by particulars of the hard drive. The only thing about the hard drives that influence the type of Array is the total number of drives in use. The rest of the Array is controller or OS dependent. I don't know where you are getting those specs. Maybe you could link to them so someone could explain what you are reading.


***Hey I run Intel... but let's get real***

 

[blah]

http://www.promise.com/ will explain it plain and simple... heh, you guys are cracking me up...

K7 + KT7 + MX300 + VD3000 =

 

[Guest]

RAID is the hot thing in storage now days and so IBM is taking advantage of those that don't know about RAID. The drive will work just fine for you so don't worry about it, get the drive and stuff it in your box.

Mike

 

[Guest]

"In such a configuration, unlike SCSI, IDE drives are always available to the system. SCSI requires more managment of the SCSI bus." What in the hell are you talking about, have you even run a RAID 0 or 1 or 5 array in hardware or software? Scsi drives will run circles around ATA (Not IDE)
beacuse of their command quing and out of sequence execution of commands. You might want to read a little more about the SCSI standard and the drives.

Mike

 

[Lars_Coleman]

Thanks Mike.

Email Promise and tell them they don't know what they are talking about cause I got that from there site!



Lars Coleman

 

[Guest]

I would be happy to, you in the other hand need to remember that Promise is an ATA card maker and that they have to compete with the dominant and superior interface in the storage market and as such are probably not above a bit of twisting of the truth to try and make their product look better. The fact is that SCSI is the better way to go for high performance RAID support and expandability. That also said, the Promise RAID controler is quite a card with 6 seperate ATA100 channels on it and the performance is most likely very, very good even compaired to SCSI based RAID arrays.

You need to read all of the info before first, not just the pretty front page stuff.

Mike

 

[Guest]

'...While RAID 1 is the least efficient use of hard drives to provide data protection (since the user does not see any of the additional storage capacity of the mirrored drives)...'

I somewhat disagree on that..

On a low-cost server built for a availability, the RAID 1 is the most cost-efficient, mirroring the data. Also RAID1 is faster than a single drive and other RAID-systems I know.

Jet no point having it on a PC

And they said schizophrenia is annoying?

 

[Guest]

yeah but it's limited to two drives only.. so really what you probably see used more often is RAID 01/10 in those cases.

***Hey I run Intel... but let's get real***

 

[Guest]

Raid 1 is slower on writes but quicker on reads than one drive but against a RAID 0 with two disks in the stirpe it isn't any faster and if there are three disks in the stripe then it is way slower. Now as far as data safety and speed there is only one way to go and that is RAID 5+1. Striping with parity and a spare for on the fly rebuild of the data on the failed disk.

Mike