RAID...?

[roseusa]

i never configure any kind of RAID. i want get some experince and knowledge for this. Can you guys help me for this, also i have few questions...

which RAID is for what kind of work...?
how many HDD i need for RAID....?
how to configure with physicaly and how with software ...?
is it ok if i have different size of HDD....?
is it also possible if lets say i have 1TB HDD, if i make different partions and just put in RAIS these partions...?
and how data is save if some thing happened to any one disk...?


sorry for any stupid question... as i mentioned i never did this before and i want to learn...

Thanks

 

[mscallisto]

There are many ways to setup RAID0 thru RAID5 with 2 or more drives and there is also a software version both too lengthy to explain in this thread so see the link below or other links from a google search of RAID

http://www.hardwaresecrets.com/article/393

sam

 

[Freestone]

Another good guide to RAID:

http://www.pcguide.com/ref/hdd/perf/raid/

 

[linney]

How to Set Up a RAID Array

http://www.pctechguide.com/tutorials/RAID.htm

 

[wahnula]

Quick rundown of the most popular RAID levels:

RAID 0: No redundancy, just speed, speed, speed. Fastest setup around. Good for anything that requires intensive hard drive access but backup, backup, backup. Minimum of (2) drives, total space will be smallest drive x number of drives.

RAID 1: Simple mirroring, slower to write, faster to read. Good for data redundancy and stability, like operating systems and applications. Minimum of two drives, total space will be the same as smallest drive. You can also "nest" this level with RAID 0, see the guides above.

RAID 5: Good compromise of speed & redundancy, minimum (3) drives, total space available will be the smallest drive times the number of drives minus the space of (1) drive. Example: (4) 100GB drives will yield a 300GB RAID 5 array.

This is a pocket guide to get you started, I second Freestone's recommendation of the PC Guide's article.

Tony

Users helping Users...

 

[roseusa]

very good informations, thanks for all of you. i will be back if i need more info or help.

 

[LawnBoy]

<cough>

RAID 1: Simple mirroring, slower to write, faster to read.

Slower or faster than what? RAID1 is faster than RAID5 to write, but slower than RAID5 to read.

--
The stagehand's axiom: "Never lift what you can drag, never drag what you can roll, never roll what you can leave.

 

[BadBigBen]

<cough>

RAID 1 - Mirrored set without parity. Provides fault tolerance from disk errors and failure of all but one of the drives. Increased read performance occurs when using a multi-threaded operating system that supports split seeks, very small performance reduction when writing. Array continues to operate so long as at least one drive is functioning. Using RAID 1 with a separate controller for each disk is sometimes called duplexing.

source:

http://en.wikipedia.org/wiki/RAID

it takes not much to know that what Tony wrote on RAID 1 refers to RAID 0... </cough>

Ben

"If it works don't fix it! If it doesn't use a sledgehammer..."

 

[LawnBoy]

Gad, why the wikipedia quote?


--
The stagehand's axiom: "Never lift what you can drag, never drag what you can roll, never roll what you can leave.

 

[BadBigBen]

To back up Tony's short statement! - LOL a bit overdone, I guess...


but you asked... LOL...

Ben

"If it works don't fix it! If it doesn't use a sledgehammer..."

 

[LawnBoy]

I just got confused as to what wahnula's 'faster' and 'slower' were referring to. I think we agree that:

RAID0: reads faster than 1 but slower than 5, writes faster than 1 or 5 - no redundancy

RAID1: reads slower than 0 or 5, writes faster than 5 but slower than 0

RAID5: reads faster than 0 or 1, writes slower than 0 or 1

Summarized in a chart at

http://www.storagereview.com/guide2000/ref/hdd/perf/raid/levels/comp.html

which precedes apparently the same article that Freestone linked.

--
The stagehand's axiom: "Never lift what you can drag, never drag what you can roll, never roll what you can leave.

 

[BadBigBen]

Yep, we agree...

PS: to some people, Wiki is the easiest to understand, it tends to be less technical than some of the Tech Sites out there...

Ben

"If it works don't fix it! If it doesn't use a sledgehammer..."

 

[drjohnbullas]

the decision is faster safer or both.... if you run a RAID card with the controller on the chip on the card it might be more robust than trying to do it in software... two drives can EITHER save the same data (MIRRORING) so one drive can fall over and recover the data from the other later OR two drives can speed things up by working together to take alternative chunks of data (STRIPING) so both can be saving together OR you have four drives giving you together both fast saving and redundancy ( the data is mirrored and striped between the drives) ..... I put together a small RAID array of four drives (EBAY) and adaptor cards (EBAY) run by an ADAPTEC PCI SCSI controller card (EBAY) with memory upgrade (EBAY) which between them give me both, ONCE 'something' went wrong and the controller card happily beeped at me on bootup to fix it and the program on the card then sorted the problem ( tooka while for the data to swoosh around the 4 drives) .... it was a personal challenge for me to do it to see if I could ( I'm a geologist #1, IT bod #2) ..... lovely sequence of flashing lights !!!!

http://www.flickr.com/photos/johnbullas/969132843/

 

[drjohnbullas]

Ah.... you want seperate drives for RAID as the whole concept is you can get data security (preservation) if one drive out of a number physically fails and speed as you sequentially write to seperate spinning disks among a number, both these benefits cannot be achieved if you are writing to partitions on the same rotating hard disk, the mechanisim fails and both virtual drives could be lost and the data would have to be written by the single head....

 

[wahnula]

Wow...go away for a coupla days and I've been mis-constroodled once again in an attempt to be succinct. All my comparisons were to single-disk...

BBB...nice to know you've got my back when LawnBoy starts <cough>ing


Tony

Users helping Users...

 

[roseusa]

Two question if some body can explain

if i have any RAID, as mentioned above it mirroring on other drive, so if HDD "A" got some problem e.g data erased, virus attack or what ever, so is not this all things copied to HDD "B" for mirroring. or how it works for to prevent thes things.

can any one point me any web site where they explained with diagrams too, so i can understand in better way how exactly RAID works.

i have 2 computers MB sports RAID, while one computer does not, so what kind of CARD/hardware i need for RAID. Also any minimum RAM, cpu speed etc etc needed for RAID...?

My appologize for, if i asked any stupid question.

Thanks

 

[cmeagan656]

This link gives a detailed explanation of all the variants of RAID:

http://www.bit-tech.net/hardware/2007/06/11/understanding_raid/1

Cheers.

 

[BadBigBen]

if i have any RAID, as mentioned above it mirroring on other drive, so if HDD "A" got some problem e.g data erased, virus attack or what ever, so is not this all things copied to HDD "B" for mirroring. or how it works for to prevent these things.

it doesn't... RAID 1 or 5 are there only for hardware (drive) failures, thus keeping the DATA redundant and accessible, where as RAID 0 is for capacity and speed...

can any one point me any web site where they explained with diagrams too, so i can understand in better way how exactly RAID works

either see the the WIKI page I outlined above, or cmeagan656's site given...

My apologize for, if i asked any stupid question.

there is NO such thing as a Stupid Question... ;-)

so what kind of CARD/hardware i need for RAID.

a PCI card that either supports IDE or SATA RAID... e.g. Rosewill RC-200 PCI IDE (ATA) Silicon Image RAID (0/1/0+1/JBOD) Host Controller Card - Retail

http://www.newegg.com/Product/Product.aspx?Item=N82E16816132004

or Accusys ACS-61100-12H PCI Express SATA II RAID Card - Retail

http://www.newegg.com/Product/Product.aspx?Item=N82E16816121017

but you be aware that there are things like SOFTWARE RAID on some of these cards, which take processing power away; where as a TRUE RAID card (like the last) are controlled by hardware and firmware on the card...

Also any minimum RAM, CPU speed etc etc needed for RAID...?

32mb RAM, a minimum of an Intel 386 running at 14mhz if I remember correctly, depending on the raid at least 2 drives or more...

Ben

"If it works don't fix it! If it doesn't use a sledgehammer..."

 

[roseusa]

great, i am learning very quick from you gurus, thanks for all of you.

 

[LawnBoy]

I've been mis-constroodled

I simply asked you for clarification of your post. The guy who "had your back" misconstrued you with

it takes not much to know that what Tony wrote on RAID 1 refers to RAID 0... </cough>

so please don't accuse me of misrepresenting your post.



--
The stagehand's axiom: "Never lift what you can drag, never drag what you can roll, never roll what you can leave.