RAID1 Q's

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bcass
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RAID1 Q's

Post by bcass » Sat Apr 09, 2005 1:29 am

As a result of a HDD failure I am going to buy a RAID1 S-ATA PCI card. I know that RAID1 basically mirrors 1 drive using 2 drives, and if one fails, the other is used. How good is this in practice though? If one fails, and you have to replace 1 drive in the array, is it just a case of taking the bad one out and putting a new one in (of the same size)? In which case, is all the data from the good drive automatically transfered over to the newly installed drive? How is the user made aware of a failure in one of the drives? Also, how does this work if the two mirrored drives have the OS on them and one fails? Will the OS happily transfer over to the newly installed drive in the array?

In addition, can anyone recommend a really good S-ATA RAID1 IDE card? I need something that is ultra-reliable and user-friendly in the event that one drive in the array needs replacing. It needs to support 48-bit LBA (HDDs > 137Gb) and bootable array support. It also needs built-in support for first-party DMA to eliminate bottlenecks associated with on-board DMA. I will be using it with an ASRock K7S8XE. This has PCI IDE BusMaster support, if that helps.

Finally, I also intend on getting a normal IDE RAID1 PCI card for use with two 250Gb HDDs (acting as mirrored data drives). Will my 350W PSU be enough to power this lot?

Thanks in advance for any help.

jojo4u
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Post by jojo4u » Sat Apr 09, 2005 3:16 am

This might answer some of your questions.
http://www.tweakers.net/reviews/557/1

Tigr
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Re: RAID1 Q's

Post by Tigr » Sun Apr 10, 2005 1:24 pm

bcass wrote:As a result of a HDD failure I am going to buy a RAID1 S-ATA PCI card. I know that RAID1 basically mirrors 1 drive using 2 drives, and if one fails, the other is used. How good is this in practice though?
It is as good as it says. If only one HDD fails, your data is perfectly safe. Of course, if both drives fail or something goes terribly wrong in the controller and it overwrites your data or something like that... But otherwise a good idea for important things.
bcass wrote: If one fails, and you have to replace 1 drive in the array, is it just a case of taking the bad one out and putting a new one in (of the same size)?
Normally, yes. You take out the failed drive and place a new one in. The new drive can be of bigger size too (some place will end up unused). It may be interesting to have a "stand-by" HDD there as well so that it is automatically used by the controller to rebuild the array should one of the drives fail.
bcass wrote: In which case, is all the data from the good drive automatically transfered over to the newly installed drive?
This really depends on the controller. Usually you would enter the RAID BIOS at the start-up and tell it to rebuild the array. Can be done from under the OS too.
bcass wrote: How is the user made aware of a failure in one of the drives?

It depends on the drivers and tools you are running. There will surely be some way that the software notifies you.
bcass wrote: Also, how does this work if the two mirrored drives have the OS on them and one fails? Will the OS happily transfer over to the newly installed drive in the array?
The OS is totally unaware of the RAID (well, almost, anyway) if you use a dedicated hardware RAID card. For OS, it does not matter whether your RAID is fully operational or is running in a degraded mode under some failure condition. The data is there so it does not matter.
bcass wrote:Will my 350W PSU be enough to power this lot?
I currently run two IDE PCI cards with 4 drives from a 400 W PSU. I doubt I am using even half of that power capability. I am sure it will be ok to run 4 HDDs from that PSU but, again, you will have to try and see for yourself...

BTW, if you really go high-end RAID cards, they usually support 64 bit PCI, so getting one of the motherboards that support 64 bit PCI would really improve the throughput of your hard disk subssytem. And it would be cheap compared to the price of one of those RAID controllers :P

bcass
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Post by bcass » Wed Apr 13, 2005 12:26 am

Thanks for all the info. Much appreciated. I think I will get the RAID1 cards and also implement some sort of backup at a later date (when finances permit).

Can anyone recommend a really good RAID1 S-ATA IDE card (and a normal RAID1 IDE card)? They need to support 48-bit LBA and on-board Bus Mastering.

sthayashi
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Post by sthayashi » Wed Apr 13, 2005 4:44 am

bcass wrote:Thanks for all the info. Much appreciated. I think I will get the RAID1 cards and also implement some sort of backup at a later date (when finances permit).

Can anyone recommend a really good RAID1 S-ATA IDE card (and a normal RAID1 IDE card)? They need to support 48-bit LBA and on-board Bus Mastering.
I've used Highpoint's RocketRaid 404 successfully for the last few years. No idea if it does Bus Mastering though.

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