NAS Raid question. Raid 1, 3, or 5.

[protokatie]

At some point in the forseeable future I will be setting up a Raided NAS for all my files/movies etc. I was thinking of having 4 500GB drives, in 2 sets of Raid 1 (for a total of 1 TB of total storage). I will ofcourse also be making backups of the data, and wont be relying on Raid for data security only.

Any suggestions on which Raid would be best for my potential setup? Also, I was planning on going the software route for the raid array, since the only files I would be accessing would be media files, and usually only one at a time, something that doesnt require a massive amount of HD read speed (I wont be using the raid to store live TV or anything). Any suggestions on low-cost or free raid software? (It would have to be able to work with any partition in a custom box, as I may mix up the brands of drives that I use to decrease the likelyhood of two drives failing one right after the other).

Thanx in advance. BTW, I would most likely also be using the custom NAS as the computer in my cab as well. Im not too worried about CPU performance, as I will be getting a somewhat decent machine to do this with, and the most CPU intensive games I plan on are NEOGEO.

[shmokes]

Go with RAID 5.  You get the security of RAID 1 and a lot more storage capacity.  With RAID 5 you'll only lose the capacity of one of those drives for parity.  RAID 1 will kill half your capacity for mirroring.

Also, for what it's worth, I've had a RAID 5 with 4 500GB drives for a couple of years now and I'm already reaching capacity.  If you can afford it go with 4 750GB drives or 1TB drives.  Remember, no matter how big a hard drive you get it only has two states for the most part:  New and Full.   

I've never used a software one, but I would actually recommend using identical drives if you can.  Raid controllers can sometimes be finicky about that.  My RAID array requires it.  I've seen others function, but poorly, unless all the drives were identical.  *Shrug*  maybe software will be better with mixing and matching.

[protokatie]

Hmm maybe Raid 5 is the way to go then, although I have read about how many professionals are heavily against it. Meh, for home use it should be fine. And yeah, the reason why I wanted to go the software route is I am imagining it to be much more tolerant for mixed drives.

Another thing I was thinking of was to forgo RAID altogether and use a software "auto-backup" program. Not a scheduled one, but one that monitors the target (primary) HD for writes, and calls the OS to write the file to another drive as well(dunno if this sort of thing still exists, the last time I saw one was for the Amiga). The advantages in my case for this are: Only needs to spin up the backup drive during writes (the primary is used for all reads) and as I would only be writing when adding new media would help keep wear and tear down on the local backup. Also, in this case, the backup drive can be completely different than the primary (size, vendor, disk/storage type (IE Flash, DVD-RAM, HDD, or even a folder on a network drive)).

Ideas on this? (And any links for auto-backup software?)

[orion]

If as you said you are not planning on using this machine as a secure backup to your data, then I don't see the use in raid at all. I have a NAS box whose soul purpose in life is to serve as a central place to access all my MP3's, movies and family photos on. I have everything backed up elsewhere. For this purpose I just use JBOD as I can use any junker hard drive I have laying around to add to the mix for more storage. I use Free Nas for this. http://www.freenas.org/ Whats great about it is that you can use any old Jalopy to run it... providing its at least a P3 with at least 128 megs of ram. It also has a really cool web GUI, and if you are intent on raid, it does it all.

[boykster]

Shmokes is spot on - RAID5 or RAID6 if you're interested in large storage arrays, RAID1 if you're just interested in a smaller volume with good redundancy.

I prefer hardware over software RAID, but it's possible to create a good reliable system using entirely software.  You also are definately best off sticking with drives of the same size, same vendor, and preferably same model number.  It is possible to mix and match, but again, you'll be "better off" if you stay consistant.

[patrickl]

RAID 5 is indeed the most economical option for very large arrays. On the other hand, with disks being as big as they are these days, you could actually save a lot of money with a mirroring setup. RAID 5 is slower too and it can actually make you lose everything. For instance, if the RAID hardware breaks down you could lose all your data. Besides you can still have 2 disks breaking at about the same time. Sounds unlikely, but it actually happenend to me twice. I read a suggestion that it had to do with disks being from the same batch having a higher likelyhood of crashing after the same number of hours in use.

I use both. I use RAID 5 for the file servers, but I use mirroring on the workstations and webservers. I also use the mirroring for backup purposes. There are 2 identical disks in the computer and I have one spare. Every week I swap one of the mirrored disks for the spare one.

[protokatie]

Thanks for the advice, guys. If I do go with RAID I am thinking I may stick with RAID 1.

I may even go to something much simpiler than RAID. Basically have a batch file that contains: XCOPY source dest /D /Y /V    and have it run every night. If I copy anything over to the file server that I MUST make sure is secure, I will just run the batch file after I do the file copy from my primary computer to make sure both disks have the same files. Yeah I know, kinda a ghetto way to do it, but this would be for Vids/music etc so if I lost a few movies it wouldnt kill me. It's not like I will be adding files every hour of every day, just the occassional dump from my main compy's media files to make room and allow for others on the network to access them (Like maybe once a week). Any ideas on this (very ghetto) route?

[shmokes]

Memeo made a program that would synchronize folders over the network.  I can't remember what it was called, but it came with an old Maxtor OneTouch external hard drive I bought a long time ago.  I don't see the program on their website now.

Anyway, it wasn't strictly a backup program.  After the initial backup, files were only copied over that had been changed and the copy took place immediately, not at some predesignated time.  It constantly monitored the specified folders and instantly synchronized the folders across the network, so your data always stays secure.  A really cool feature of it, though, is that you could specify how many versions of a file you wanted to keep.  So, for example, if you told it to synchronize your My Documents folder with 5 versions, it wouldn't just keep a backup, but it would let you access any of the past 5 changes.  This is super useful for those times when you don't realize that there's a problem -- say, an important file went corrupt -- until long after you've replaced your good backup with the corrupt one.  Of course, this means that the program is constantly running in the background, but the little bastard was pretty much invisible.  It didn't use any appreciable amount of resources.

At any rate, I didn't have any use for it at the time, so didn't use it enough to vouch for its stability.  But what I saw seemed pretty cool.

[orion]

http://dailycupoftech.com/windows-backup-with-rsync-and-freenas/  Is something like this what your getting at??