RAID and Spanning

Ph4lanx

Ph4lanx

Ph4lanx

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Joined
19 Apr 2010
Posts
474
Location
Surrey
Hi guys,

I've got a server running at the moment with a pair of 500GB HDDs in a RAID 1 configuration.

What I would like to do is add more HDD pairs which are also RAID 1 configured, but I ideally would like to make the new RAID 1 span onto the original RAID 1. Is this possible?

Thanks.
 
I don't have a controller, it's running via the Windows software RAID setup.

Do you think it's worth me starting over with my server perhaps? Build a proper one?

The current spec is:
PentiumD 830 @ 3.0GHz w/Stock Cooler
ASUS P5ND2-SLI
Unknown make 2GB RAM
Enermax 450w PSU
Antec 300
GeForce 9400GT
164GB HDD (OS), 500GB HDD RAID1 (Storage)

I was considering rebuilding it into a quiet, low power machine, as so far it has just been made out of spare parts.
 
You generally need to wipe RAID sets to re-build them / re-map them (note: generally).

I personally would get a decent RAID card, set-up RAID 1+0 and invest in some low cost, high density hard drive (4 x 1.5TB Spinpoint F1's for example). Bigger disks and more spindles will give you better perf, plus 1+0 is generally one of the faster setups.
 
Is it worth doing even when the server is only sat at home serving at most, 5 machines? How heavy would the usage be? Do you reckon I should respec from scratch? Perhaps use this change of disks to make a low-power, quiet server?

What kind of spec should I be looking at? I've got a few ideas but perhaps things like:

- Integrated graphics?
- "Green" HDDs?
- Smaller case?
- Quiet CPU cooler?

Also, my current RAM is DDR2, but is the old Dual-Channel DDR2 667/533 variety. I know it might be a stupid question but if I get a DDR2 compatible motherboard, will it support this old variety?
 
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667/533 is just the Mhz (speed); providing it is a DDR2 compatible board your fine. I would re-use it all TBH just buy new disks / more disks, the hardware is more than fine to run a home file server.
 
OK cool that's good. Some people have talked about using RAID5. I've never done anything more than RAID1 or RAID0. I've read up on Wikipedia about RAID5, but I'm not sure just how strong this is as a system to make sure I don't lose data.

I was under the impression that RAID1 meant that if one HDD fails, the other continues until I replace the failed HDD and tell it RAID the whole thing again. Is that not right? What does RAID5 do that RAID1 doesn't, other than this "parity" thing that I don't really get. Remember I'm running this through the OS/Software RAID configuration.

Sorry for the questions on RAID, I'm just not sure on it completely, as I've never really used anymore than RAID 0 or 1.

Also, when replacing a drive in a failed RAID array, is it just a case of placing the new drive in and then doing something to tell it to start mirroring once more?
 
Easy way to remember it, is RAID 0 gives you 0 protection.

RAID 1 is mirroring, so if you have 2 x 750GB drives, the data will be written by the RAID controller to both drives consecutively.

RAID 5 is good, but you need more disks for 1 - and it doesnt cover for a double drive failure also. Your choice of RAID 5 depends on what we call your stripe size, but i wont get into that - the best perf "talk through" is avail here:

http://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_5_performance

Me personally, I'd just get 2 RAID 1 volumes, Volume 1 (2 x 1TB) and Volume 2 (2 x 1TB), and then mirror beetween the 2 (either RAID 0+1) or easier, just rsync.
 
And yeah, when a drive fails you either have to manually initiate copyback to the new drive, or the RAID controller will detect the new drive and initiate it for you. Depends really.
 
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