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Old 11-09-2008, 02:09 PM   #21 (permalink)
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Default Re: Why do people put two hdd's in their comp?

Ok, tin ie? If raid 0 isn't that much faster than raid 1, how come like if you see a youtube video or something that is showing off a gaming rig, if they make any reference to raid at all, they say raid 0?
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Old 11-10-2008, 03:28 PM   #22 (permalink)
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Default Re: Why do people put two hdd's in their comp?

Quote:
Originally Posted by Druid View Post
Ok, tin ie? If raid 0 isn't that much faster than raid 1, how come like if you see a youtube video or something that is showing off a gaming rig, if they make any reference to raid at all, they say raid 0?
Let me say that I dont think that a person recording their PC and then posting it on youtube is the best place to pick up tips.
RAID means Redundant Array of Independant/Inexpensive Drives so when I say that it doesn't do what it says on the tin I mean that it does not offer any redundancy, I was not referring to speed in any way. RAID 0 is very fast but that does not mean that it is 'good', with RAID 0 not only do you get no redundancy, your system is more likely to fail.
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Old 11-10-2008, 03:56 PM   #23 (permalink)
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Default Re: Why do people put two hdd's in their comp?

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RAID 0 implements a striped disk array, the data is broken down into blocks and each block is written to a separate disk drive
I/O performance is greatly improved by spreading the I/O load across many channels and drives
Best performance is achieved when data is striped across multiple controllers with only one drive per controller
No parity calculation overhead is involved
Very simple design
Easy to implement

Raid 1 - One Write or two Reads possible per mirrored pair
Twice the Read transaction rate of single disks, same Write transaction rate as single disks
100% redundancy of data means no rebuild is necessary in case of a disk failure, just a copy to the replacement disk
Transfer rate per block is equal to that of a single disk
Under certain circumstances, RAID 1 can sustain multiple simultaneous drive failures
Simplest RAID storage subsystem design

Raid 5 Highest Read data transaction rate
Medium Write data transaction rate
Low ratio of ECC (Parity) disks to data disks means high efficiency
Good aggregate transfer rate


Disadvantages
Not a "True" RAID because it is NOT fault-tolerant
The failure of just one drive will result in all data in an array being lost
Should never be used in mission critical environments

Highest disk overhead of all RAID types (100%) - inefficient
Typically the RAID function is done by system software, loading the CPU/Server and possibly degrading throughput at high activity levels. Hardware implementation is strongly recommended
May not support hot swap of failed disk when implemented in "software"

Disk failure has a medium impact on throughput
Most complex controller design
Difficult to rebuild in the event of a disk failure (as compared to RAID level 1)
Individual block data transfer rate same as single disk
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Old 11-10-2008, 10:47 PM   #24 (permalink)
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Default Re: Why do people put two hdd's in their comp?

Ok, so with Raid 0, how many times faster will app and in game load times be than other raid and non-raid configurations? This will make you start up time less as well?

Why will raid 0 make you more likely to fail than with a non-raid configuration?

Is raid 1 any slower than a non-raid configuration?

Say one of your drives fail in raid 0, you then have to format the other drive?

Say one of your drives in another raid formation such as raid 1, do you just copy the data from the functioning drive to the new drive you bought? Say you couldn't find the same hdd you were using before, can you buy a different one and still raid?
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Old 11-11-2008, 02:41 AM   #25 (permalink)
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Default Re: Why do people put two hdd's in their comp?

It depends on what drives your raiding together as tro the performance increase it can be a 10-40% performance boost with raid0

raid0 is more likely to fail as your doubling up the number of mechanical components from asingle drive config. If one of the drives is a bit dodgy and dies the data from both the drives is lost this called redundancy. Raid 1 is a lot more secure as there are always multiple copies of the same data so if one drive dies it doesn't matter. Raid0 you only have half the data on the working drive so data is very difficult to recover.

Raid 1 is slower when writing data but faster when reading data

If a drive dies in Raid0 you don't HAVE to reformat you can get the data off but will cost you quite a lot of money most peopl just take the loss and move on.

Raid arrays like Raid 5 and Raid 1 can rebuild and repair themselves so are dynamic if you add more drives to the raid array. You can raid between any harddrive with any other harddrive the capacities need to be the same though otherwise your just losing gb for nothing. If you use a 100gb drive and a 320gb drive in Raid 1 you will only have 100gb of usable space, in Raid 0 you will have 250gb (100gb from the 100gb and 150gb from the 320gb) and raid 5 wouldn't work with just 2 drives so add an extra 320gb. 2x320gb and a 100gb in raid5 would give you 640gb of usable space as the 100gb would be used as the redundancy drive
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Old 11-11-2008, 02:27 PM   #26 (permalink)
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Default Re: Why do people put two hdd's in their comp?

A couple of minor things in your last paragraph:
You cant add more drives to a RAID 1 but it RAID can be rebuilt if one drive fails;
Unless there is something i'm not aware of you would only get 200GB (2 * 100) from the RAID 0;
You would also get 200GB from the RAID 5;
RAID 5 does not have a redundancy drive;
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Old 11-11-2008, 02:48 PM   #27 (permalink)
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Default Re: Why do people put two hdd's in their comp?

Google it, you'll get a much more thorough answer.

Redundant Array of Independant Disks, there are a few different configurations. But the gist of it is you have data copied on multiple disks, so if one fails you have the data (or part of the data) on another disk. The RAID controller does this for you so it is constantly copying the most up-to-date data and files to all drives - this way the CPU isn't bogged down by it. The most common RAID config. are:
0 - (Requires 2 disks) Disk stripping, this provides NO data protection, it just allows your system to run faster because pieces of the data are on each drive, essentially allowing the OS/RAID controller to grab more data at once.
1 - (Requires 2 disks) Mirroring, you have two drives that are identical. If one fails, you replace the failed drive with a new one and rebuild the array based off the other drive that is still good.
5 - (Requires 3 disks) This uses parity to place bits of information on all three drives. As most know all computers are is mathmatical machines, and all data and files are a mixture of 1's and 0's. Parity takes a file apart and creates an equation, the parity of the equation is the total of both halves. So 1+1=2, each number being on a different drive. So if you lose the first 1, we can rebuild the array with the remaining 1 and the parity information of 2.

There are lots of other RAID configs out there, but these are the most common.
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Old 11-11-2008, 04:54 PM   #28 (permalink)
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Default Re: Why do people put two hdd's in their comp?

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Originally Posted by KMOTE View Post
A couple of minor things in your last paragraph:
You cant add more drives to a RAID 1 but it RAID can be rebuilt if one drive fails;
Unless there is something i'm not aware of you would only get 200GB (2 * 100) from the RAID 0;
You would also get 200GB from the RAID 5;
RAID 5 does not have a redundancy drive;
Your wrong about Raid 0 for sure it gives you 150% of the single drive if the secondary drive has more volume.

Raid 5 uses a redundancy drive so that it can rebuild the raid array should a drive fail thus the final drive is a redundancy drive
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Old 11-11-2008, 06:44 PM   #29 (permalink)
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Default Re: Why do people put two hdd's in their comp?

I dont know where you have got this information but I'm afraid it is wrong. In fact if you look at the information in your sig you will see that RAID 5 uses distributed (or rotating) parity <b>not</b> a dedicated parity drive. I would like to see where you got that information on RAID 0 as well as that is also wrong, where for example is your "secondary drive" defined? And how do you arrive at the specific 150% figure. What if, for example your "secondary drive" is not at least 1.5 times the size of your "primary drive"?
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Old 11-12-2008, 06:07 AM   #30 (permalink)
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Default Re: Why do people put two hdd's in their comp?

True its a distributed parity but the size of the parity on each drive is proporionate to one of the disks on its own therefore it is said that one hdd is a parity drive even though this isn't the physical case. It is the sum of the total disk space minus one of the hdds space that you get in raid 5 so 5x100gb - 100gb = 400gb of usable space like losing a single drive for parity. Raid 4 is similar to raid 5 but a single physical disk is used for parity, Raid 5 its a virtual disk lost to parity.

I thought Raid0 could account for different raid sizes upto 150% of the smallest drive but a quick google didn't give any evidence for this sorry for misleading you.
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