RAID noob

[The111]

I just built a new system, ASUS P5W-DH mobo, and one SATA HDD, 250GB.

I have never done anything with RAID, but I understand RAID 1 is the "mirrored array". Is it possible to buy two 400GB SATA drives, hook them up as a RAID 1 array for important data, and maintain the 250GB drive as non-RAID, like it is now, for my O/S and software? So I would have 3 drives total... but from O/S I would see one 250GB and one 400GB (mirrored) drive.

Also, the mobo has something called "ASUS EZ RAID" in addition to "normal" RAID, I guess. Any thoughts on this?

Thanks.

 

[The111]

bump?

 

[Bobthelost]

Yes it is possible (and you're exactly right about how it'd work too), the Asus EZ RAID is just a way of setting it up. No idea if it's better or worse than the system that comes as part of the chipset (or if there is any difference).

 

[Madwand1]

Briefly, an external drive used as a periodic backup and then detached will protect you from many modes of failure not covered by RAID. The difference here is that it won't protect any data from the point of last backup because it won't have it. The "ideal" solution would be some sort of active replication / HD redundancy with an external backup. Short of that, and the reason for this post, is that IMO a backup is generally better than RAID 1.

(And yes, you can implement detached backups using RAID 1, but in this case the logical mode of operation is backup more so than RAID 1 although the implementation is RAID 1 make & break & re-build.)

 

[bullfrawg]

While we're on RAID, I've got a question. Can you buy 2 drives that are the same size, partition them identically, and have RAID 0 on one partition, with RAID 1 on the other? So say you got two 160 GB drives. You partition each so that you have a 60 GB partition and a 100 GB partition. Then you run RAID 0 on the two 60 GB partitions, and put your OS and your programs on here. The 100 GB partitions are linked in RAID 1 for your data.

Now when you are starting programs, or when your operating system is accessed, you have fast boot times of RAID 0. Your data is read from the RAID 1 at the normal speed. If one drive fails, you don't lose any data; you lose your program files, but you can reinstall them from CD.

It seems like this could work in theory, but I don't know whether it's supported in the actual hardware and software. Anyone know? (I sure don't.)

 

[Madwand1]

Intel's "Matrix" RAID does this, but partitioning is generally a degradation in performance compared to multiple drives, so don't expect a lot from such a setup in terms of performance.

 

[The111]

Originally posted by: Madwand1
Briefly, an external drive used as a periodic backup and then detached will protect you from many modes of failure not covered by RAID. The difference here is that it won't protect any data from the point of last backup because it won't have it. The "ideal" solution would be some sort of active replication / HD redundancy with an external backup. Short of that, and the reason for this post, is that IMO a backup is generally better than RAID 1.

(And yes, you can implement detached backups using RAID 1, but in this case the logical mode of operation is backup more so than RAID 1 although the implementation is RAID 1 make & break & re-build.)

That's interesting, although I don't fully understand it. I currently have two external drives which I refer to as my "ghetto RAID" system. I manually mirror my data (photos and video, mainly) across both drives on a weekly basis, and then once every few months I dump all the data to DVD-R's. I also make mirrored sets of the DVD-R's, because I don't trust optical media and have had it fail before. But the external solution is not making me feel too good, mainly because one of the two drives (a Maxtor 250GB) keeps corrupting itself somehow. I will have a folder with 1000 other folders inside it, and after a few months about 800 of those folders will just disappear into thin air. I usually re-format the drive, fix bad sectors, and re-populate it, and inevitably it always goes bad again after 6 months or so. I think it's definitely screwed up, and I've had other problems with external USB drives before. This, in addition to the extra manual effort required to maintain the "ghetto mirrors", led me to think that going to a true internal RAID system (which I never took the time to learn about before) would be a better idea.

I am curious what you mean by "modes of failure not covered by RAID".

Also not sure exactly what you mean by "some sort of active replication / HD redundancy with an external backup".

I am definitely interested in learning more about this... I shoot a lot of digital photo and video and want it to last forever and am not sure I'm going about it the best way.

 

[Madwand1]

Originally posted by: The111
I am curious what you mean by "modes of failure not covered by RAID".

(A) RAID 1 will cover you for a single HD failure, assuming the RAID was set up properly and it works properly. But this is just one thing -- what if the RAID controller fails? What if the BIOS / OS messes up the RAID configuration / partition? What if 2 drives fail? Failure during recovery? Malware? Software error? User error? ...

Originally posted by: The111
Also not sure exactly what you mean by "some sort of active replication / HD redundancy with an external backup".

(B) RAID 1 is one example of "some sort of active replication". This generalizes further to other types to external storage / servers as well. What I meant was along the lines that RAID 1 + backup > just backup > just RAID 1.

It looks like you're on the right track already in terms of multiple external backups, etc., but I think you should pursue the external backup problems further and not just replace them with RAID 1 (for reasons given in point (A) above). Perhaps there's something wrong with the HDs being used for external backups. HDs fail after all, and if they start failing repeatedly, it's time to stop using them. Perhaps there's a file system / USB / drive enclosure problem; I can't diagnose the problem here, but there are many different ways to solve / work around this problem.

An internal drive that is detached most of the time can also function as a backup. Doing this with a RAID 1 implementation that's made and then broken is not uncommon -- but the backup has to be inaccessible most of the time to hope to address point (A). For point (B), there could be two or more external drives that are cycled through -- one being the active copy, others being older copies. But to do this successfully, you have to know what you're doing with the RAID implementation, and how it behaves, which generally means having a full backup somewhere before you start playing with RAID 1 implementations.