Network-Attached Storage (NAS)

[feather]

Gonna build one of these at some point and run RAID5.

Any of you guys using NAS already? Feedback, tips, etc?

Can you run RAID5 with 3 disks or must it be 4? Wiki tells me a minimum of 3, but their diagram shows 4.

I will want an NAS with a built-in BT client so I can take all the load off my Macbook Pro.

Better to buy a NAS with BT, or build a mini-computer?

[Funky Dredd]

Re: Network-Attached Storage (NAS)

In order to have RAID5 you need 3 disks or more. I can't comment much on the NAS because I don't use them. I can tell you how to carve a chunk off on a SAN though

[feather]

Re: Network-Attached Storage (NAS)

Cool thanks, will probably start with 3 disks then.

[Funky Dredd]

Re: Network-Attached Storage (NAS)

The more the better. I always use 5 disks, but I work for a hospital and those disks are important (extremely).

[thesightless]

Re: Network-Attached Storage (NAS)

beanz runs AIDS, its close, might help

[feather]

Re: Network-Attached Storage (NAS)

The more the better. I always use 5 disks, but I work for a hospital and those disks are important (extremely).

5 disks? Does more = less corruption should failure occur?

[Funky Dredd]

Re: Network-Attached Storage (NAS)

No but you can lose 2 disks and still be good. Remember I work at a hospital and data is extremely important.

[res0nat0r]

Re: Network-Attached Storage (NAS)

In a classic raid5 setup you can only lose one disk maximum before data loss will occur. therefore you could technically have 11x1TB disks and get 10TB of usable diskspace, the last 1TB drive being used as parity. the parity for the entire volume is striped across all disks in the volume and therefore can with a loss of one disk the data can be recovered. But the higher number of drives the greater the chance of a disk failure, therefore the faster you need to repair it before dataloss, or also a higher MBTF which could have two disks fail at the same time which would mean goodbye data. it sounds like dredd above is doing something with double parity, probably raid6 or a hotspare, since he says that hospital data is so important this is common and can survive more disk failures before the data gets corrupted, but for normal raid5 it is one disk failure max before you are SOL.

most diagrams seem always reference 4 drives for raid5 but the max you would need is 3 to start. another issue is you need to be aware that you might not be able to online relayout your raid setup if you decide to add another drive in the future. therefore you have 800G of data on your setup and its almost full and you cant expand it w/o destroying it and recreating it. so you will need someplace to temporarily put that 800G while you recreate your volume. i think this can vary based on underlying raid card / volume manager program though so dont quote me.

this also is good explaining the different basic raid levels, with pics:

http://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_5

[feather]

Re: Network-Attached Storage (NAS)

another issue is you need to be aware that you might not be able to online relayout your raid setup if you decide to add another drive in the future. therefore you have 800G of data on your setup and its almost full and you cant expand it w/o destroying it and recreating it. so you will need someplace to temporarily put that 800G while you recreate your volume.

WTF ... is this the same with all RAID?

[shosh]

Re: Network-Attached Storage (NAS)

heres a demo video that might help you with NAS:

[YOUTUBE]nMn2cCBwH18[/YOUTUBE]

[|Thrax|]

Re: Network-Attached Storage (NAS)

one of my favorite rap songs of all time.

[Funky Dredd]

Re: Network-Attached Storage (NAS)

it sounds like dredd above is doing something with double parity, probably raid6 or a hotspare, since he says that hospital data is so important this is common and can survive more disk failures before the data gets corrupted, but for normal raid5 it is one disk failure max before you are SOL.

Yes I have it setup as a hot spare.

WTF ... is this the same with all RAID?

Yes. There is no way to add a disc to your RAID later for more space. Although I shouldn't say that, because you can add more space if you are using a SAN. If you have a SAN and you are running out of space on your LUN you can expand that LUN by creating a MetaLUN and then run diskpart (on Windows) and then expand it. Providing the expansion LUN is setup in the same RAID that the original LUN's RAID is. You cannot expand a LUN that is RAID 1/0 with a LUN that is RAID 5. They have to be the same (RAID 1/0 to RAID 1/0). Of course a SAN is most likely out of your budget (I know it is for mine)!
But like I said I don't know to much about NAS devices, so this could be possible to do. I would have to do some reading in order to determine that.

[venture37]

Re: Network-Attached Storage (NAS)

check out freenas.org

[feather]

Re: Network-Attached Storage (NAS)

Hmmm that looks interesting, it seems to come with bittorrent. But software RAID? Is that slower than hardware RAID? Any cons?

[venture37]

Re: Network-Attached Storage (NAS)

If you're handy with a soldering iron but a Thecus N1200 & check out http://www.openbsd.org/socppc.html

If the NAS is only going to be used by yourself you'd be better off going for RAID1, RAID 5 is overkill, adds the cost of an additional disk & will put a load on the CPU if you're using software RAID or a pseudo controller.