RAID Question

AlwaysSomething

I'm considering getting a NAS, and using RAID1 for data redundancy. A question occurs to me. If the NAS was to fail (the box, not one of the drives), could i pull out a drive and put it in a USB enclosure to get at the data? I'm thinking the answer for RAID1 is yes. If I go to RAID 5, I'm thinking the answer changes to no. AM I right?
Thanks.

jayme1

AlwaysSomething wrote: »

I'm considering getting a NAS, and using RAID1 for data redundancy. A question occurs to me. If the NAS was to fail (the box, not one of the drives), could i pull out a drive and put it in a USB enclosure to get at the data? I'm thinking the answer for RAID1 is yes. If I go to RAID 5, I'm thinking the answer changes to no. AM I right?
Thanks.

With RAID 5 almost certainly no, also with RAID 1 it would also be likely it would be a no.

A lot of NAS use a proprietary RAID solution which prevents you using the RAID in any other hardware, meaning you have to put the drive in a replacement identical NAS to get your data, this is a common problem with using RAID on motherboards.

It varies by NAS though.

closed

wouldn't a nas with usb interface be enough? raid is a little ott for non critical use, and doubles up the cost of running it.

John_Gray

You want to look at a diagram which shows the distribution of data within a RAID 5 system across the various drives!

esuhl

If the RAID-implementation on a NAS uses the kind of "fakeRAID" controllers you get built-in to motherboards, then it will be a proprietary implementation and, if the NAS dies, the only way to read the drive will be to via an identical NAS device (same model & subversion).

In my opinion, RAID mirroring is only really of use on a server where it might be important to be able to replace a failing hard drive without any down-time. And RAID striping is probably only useful if you really need to boost I/O performance and don't mind the greater risk of data loss...

DevCoder

John_Gray wrote: »

You want to look at a diagram which shows the distribution of data within a RAID 5 system across the various drives!

Raid 5 would be

D1  D2  D3  D4  D5
B1  B2   B3  B4  P1
B5  B6   B7  P2  B8
B9  BA   P3  BB  BC
BD  P4   BE  BF  BG
P5  BH   BI  BJ   BK

Where D is Disk (1-5) and B is Byte and P is Parity

Would it not?

jtk174

AlwaysSomething wrote: »

I'm considering getting a NAS, and using RAID1 for data redundancy. A question occurs to me. If the NAS was to fail (the box, not one of the drives), could i pull out a drive and put it in a USB enclosure to get at the data? I'm thinking the answer for RAID1 is yes. If I go to RAID 5, I'm thinking the answer changes to no. AM I right?
Thanks.

Raid 5 requires a minimum of 3 disks. So if your nas is a 2 drive version, then Raid 1 would be the way to go. Raid 1 drives are simply a mirror image of each other. Whether they could be read in another machine might depend on how the raid was implemented and if software or hardware raid.
I wouldn't get too hung up on your nas failing sometime in the future. You can't really cover all possibilities, unless you spend a shed load of money and/or store data offsite as well.
For example, what happens if you use any method of Raid or even tape backup to secure your precious data and you come home from work to find your house on fire?

If you can, keep copies of valuable data offsite.

DevCoder

You should always have important data in 3 geographically disperse points.

Rule one of sysadmins