Raid Question

[Larman]

Hi all, I wasn't sure where to put this topic so I put it under here.

What I'm trying to find out is there really a "big" performance difference with Raid 0 (striping) verses Raid 1 (mirroring)? I have two 250GB HDs and I'm trying to weigh the pros and cons of which way to go.

I appreciate any feedback.

Regards
Larman :bounce:

 

[vnf4ultra]

Hello, welcome to Techspot!

Raid 0 will increase the hard drive speed overall, and give you the equivalent capacity of both drives (500gb). The con of raid 0 is that if one drive goes bad, neither will work, as they are made to be one logical unit. So it doubles the rate of failure compared to having one drive(you have two drives that could fail in raid 0 vs 1 drive if you just have one drive).

Raid 1 will give you the storage of 1 drive(250gb), and each drive will be a copy of the other drive. It is no faster than a single drive, but it gives you a backup hd if one goes bad.

 

[Larman]

Hello, welcome to Techspot!

Raid 0 will increase the hard drive speed overall, and give you the equivalent capacity of both drives (500gb). The con of raid 0 is that if one drive goes bad, neither will work, as they are made to be one logical unit. So it doubles the rate of failure compared to having one drive(you have two drives that could fail in raid 0 vs 1 drive if you just have one drive).

Raid 1 will give you the storage of 1 drive(250gb), and each drive will be a copy of the other drive. It is no faster than a single drive, but it gives you a backup hd if one goes bad.

Thanks for the input! Any idea how much faster having Raid 0 makes a system opposed to if it was one drive or "mirrored" acting as one drive?

 

[DelJo63]

A good implementation of Raid-1 can setup a read from both drives and thus avoid the lost time awaiting one arm's seek delay (ie: start both at the same time). So Raid-1 gives parallel reads and serialized writes

Raid-0 has the same opportunity to start ALL the arms seeking (eg: a raid-0 > 2 drives) and then transfer the data for both read and write. The performance boost will be proportional to the number of HDs attached (the more the better).

Typical timings for 1 hd
(seek + latency + transfer)*number of I/O requests

Raid-0
(seek*I/O requests)/num of HDs + (latency + transfer)*num of I/O requests

this factors into
seek*i/o requests vs (seek*i/o requests)/num HDs

 

[pkroks]

i have a raid 0 striping setup and would like to get rid of it... is there any way i can do this without losing the data please help. also a guide to getting rid of it would be great...

 

[Larman]

A good implementation of Raid-1 can setup a read from both drives and thus avoid the lost time awaiting one arm's seek delay (ie: start both at the same time). So Raid-1 gives parallel reads and serialized writes

Raid-0 has the same opportunity to start ALL the arms seeking (eg: a raid-0 > 2 drives) and then transfer the data for both read and write. The performance boost will be proportional to the number of HDs attached (the more the better).

Typical timings for 1 hd
(seek + latency + transfer)*number of I/O requests

Raid-0
(seek*I/O requests)/num of HDs + (latency + transfer)*num of I/O requests

this factors into
seek*i/o requests vs (seek*i/o requests)/num HDs

Thanks for the info. I'm not sure what makes one raid 0 good and one not but my configuration is two 250GB HDs.

 

[DelJo63]

use hardware raid

btw: if you're going to a RAID configuration, don't waste your time with a software only implementation. You're going to soak up extra CPU and there is a cost (ie delay) to all those cycles. By all means, get an hardware I/O controller which implements the RAID services. Do your homework as this stuff gets expensive.

 

[DelJo63]

i have a raid 0 striping setup and would like to get rid of it... is there any way i can do this without losing the data please help. also a guide to getting rid of it would be great...

The safe and most likely to succeed would (imo) be to:

capture the data files to a DVD or external USB 2.0 HD
then reset/remove the raid configuration,
reformat the HD
reinstall the OS
reinstall the applications
and (whew!) copy back your data.
​

If you're bold you might take some short cuts but make sure you get a copy
of the registry

 

[pkroks]

how would i reset or remove the raid configuration? I use nvraid manager, but i cant select delete in the options. when i startup my computer there is an option to enter the raid configuration setup. if i do this i can delete the raid striping setup but it wont let me exit the config area unless i create a new raid setup (mirroring/striping/both etc)... how do i go about doing it?

*Edit: I have tried to delete the partition from the config setup area before but i then created a mirroring item. on boot up it said there was a problem wiht booting so i went back, deleted the mirroring config and put striping back on... luckily enough my work and o.s and all was still there (as i thought that i had done something to screw up the computer)... :suspiciou

 

[DelJo63]

you should DL the manual
and see pg 5 to disable via the BIOS

 

[pkroks]

thanks will check it out! :grinthumb