RAID5 Solution and Advice

[Champman99]

Hey guys,

I am just setting one of my spare PC's as a dedicated NAS, and as I'll be storing stuff I don't want to lose I thought that Raid5 sounded like the ideal solution for me. However, I just realised that the motherboard in this PC does not support Raid 5 (its an MSI C45-770, I assumed that all modern MB's would support full variety of RAID modes)

Firstly, could someone explain the witchcraft at work in that I was told I could make a Raid 5 of 5 drives, which would be protected against any 1 drive failing (at a given time) and still give me 4/5 of the storage. I cant get my head around how that works. It seems too good to be true!

Anyway my current rather meagre plan is 3*500GB Samsung F1's giving me 1GB of Storage with 500GB redundancy. Is there a RAID card that would be priced reasonably enough that it isn't worth me changing the motherboard for a 790 series one, preferably one you have experience with and could recommend. Obviously must support Raid5

I hear people talk about "Software" and "Hardware" RAID, could someone please elaborate what this really means? My only previous experience of RAID was with a Raid0 of two drives, using the Raid controller on my P5K, which failed despite the fact that neither drive was faulty, (I think possibly the CMOS got cleared or something?) Was this a hardware RAID or software? I did it in a BIOS like screen on bootup (I sound like a complete nab, but raid just confuses me!)

If I use a RAID card is this configured from within windows, and therefore is it a software raid? (I had heard that hardware raid was preferable).

Anyway sorry for the long post, the main aim is just to let me know what my best option is for building a raid5 array of 3 SATA drives, given that my motherboard doesnt have a Raid5 capable raid controller. Thanks

[switchmode]

I have not used raid for consumer level products as included on motherboards as I have have seen people have problems sometimes.

Hardware RAID uses a specialised controller to do the job, usually on an add in board but may be otherwise. Software RAID I would think uses your main CPU to do the work, so that is probably slower but can work. The guys here may understand more.

[Funkstar]

Firstly, could someone explain the witchcraft at work in that I was told I could make a Raid 5 of 5 drives, which would be protected against any 1 drive failing (at a given time) and still give me 4/5 of the storage. I cant get my head around how that works. It seems too good to be true!

Probably more than you need to know :
http://en.wikipedia.org/wiki/RAID_5#RAID_5

I hear people talk about "Software" and "Hardware" RAID, could someone please elaborate what this really means? My only previous experience of RAID was with a Raid0 of two drives, using the Raid controller on my P5K, which failed despite the fact that neither drive was faulty, (I think possibly the CMOS got cleared or something?) Was this a hardware RAID or software? I did it in a BIOS like screen on bootup (I sound like a complete nab, but raid just confuses me!)

The RAID on your P5K was actually software RAID, even if you didn't realise it. The software is a combination of firmware on the motherboard and the controllers drivers in Windows. Virtually every motherboard RAID setup uses this method. Proper hardware RAID is expensive, but also great. It is far more robust than software or firmware RAID systems. Have a look at the link in my sig to my project, I've done some pretty funky things to my RAID cards (mistakes really) that I would never had gotten away with on any other hardware (unplugging 5 drives from a 8 drive array by mistake, and it restored just fine). Hardware RAID cards also come with very powerful, if complicated, management software. The LSI app I use for mine is a pain to use, but incredibly flexible.

If I use a RAID card is this configured from within windows, and therefore is it a software raid? (I had heard that hardware raid was preferable).

I configured mine in Windows, but I could also have configured it all from within the cards own BIOS without any OS installed on the PC as well. Windows doesn't see the 12 drives I have on my RAID cards, it just sees them as two drives, because they are just two arrays.

Have you looked into Windows Home Server? It doesn't use RAID, but it uses other techniques to provide a 'storage pool' with redundancy of your drives. It doesn't matter how these are attached, so as long as you have the SATA ports, WHS can use the drives, regardless of motherboard or controller support for RAID modes.

[peterb]

I use RAID1 on a Linux server using the Linux mdadam application. Works well. Adnatage over RAID 5 is that it only uses two drives which are mirrors) but by only using two drives reduces cost and power consumption.

Google Guide to RAID and ypu'll get lots of hits that explain what and how the various RAID levels are and how they work. BTW - avoid RAID 0 for a NAS - and remember that RAID is about resilience - not backing up - so you need to consider a back up regime.