Raid

I have experience with RAID 5/6 in my setup and haven't had much trouble. I've had the following two systems as servers at one time or another:
Intel MB with 6 SATA ports
Pentium dual-core CPU
4GB DDR3
5x500GB consumer drives, later replaced with 5x2TB consumer drives
Fedora Core
mdraid (linux software raid)

Gigabyte 790fx MB with 8 SATA ports
AMD Phenom II X4 810
8GB
Fedora Core and Ubuntu 11.10
5x2TB drives

I started with the first system, swapped the drives at one point, later on the MB, then upgraded the OS. Once the RAID was moved to the 2TB drives it hasn't been redone as it moved from one MB to the other and from Fedora to Ubuntu without trouble. That's one of the benefits of software RAID with linux, I can plug those drives into any system with mdraid installed and they will be recognized as a RAID array and available on boot. The 2TB array uses XFS, I think I used ext4 on the older array, I can't recall for certain.

The first system I found my access from my windows PC to be limited to 70MB/s or thereabouts in sustained copies over the network of large files. I never could get full gigabit speeds out of it. As soon as I swapped MBs, which included the RAM upgrade, speeds exceeded 100MB/s. I see peak speeds of 130MB/s, but typically average around 115MB/s during sustained copies of large files (based on the Windows copy dialog and my own rough estimates). Copying a large amount of smaller files results in much slower copying. I've found that I can even obtain these speeds when going over the old CAT 5 wiring my builder installed.

So software RAID with off the shelf consumer products works in my experience. I've done no special tuning with the hard drives or network cards. My server is probably a bit overkill for such a device, but I did add a nvidia card to it so it also serves as my primary XBMC system, hosts the database for XBMC, and runs the squeezebox server software. Because of this multi-purpose role I haven't tried anything like unRAID or FreeNAS.

Alas there are a lot of components in a RAID setup that can cause problems. One thing you can do is try copying to a single drive on the server, both over the network and over USB, and see how your system handles that.

Orclas Wrote:CHICKEN!!!

LOL, probably so! But I figured I would lose my a$$ on just the trips to the local Fry's store, so it was well worth $300 for the base Drobo. And naturally, just after I purchased mine, Costco offered up the Drobo FS with 6TB of storage for $800. Oh, well

Hardware raid changed recently due to the lack of TLER support as I stated in the 2nd post. Not many people know this and try tons of options to find out why their array is so slow all of a sudden....
If you run an array with enterprise level drives (seagate constellation, WD REx) then you shouldn't have a problem running hardware raid.

PS1.. Hardware raid is with a controller, like the LSI you are describing...your onboard raid is fake raid... it's the slowest option possible and if your mb dies, you are probably scr*wed....

At the moment I am running 2x10 2Tbyte drives in 2 raidz2 arrays. I have write speeds of around 130 Mbyte/s over dualport gigabit lan.
The good thing about raidz2 is that you don't need an expensive raid controller... It's softraid. Lots of people despise softraid cause it is eating up your resources.. This was true in the Pentium 3 period, but nowadays cpu's are so fast that you hardly notice cpu load.

Raidz2 is the softraid counterpart of raid6... raidz is comparible to raid5... I also have the option of Raidz3 which has 3 parity drives..

Please google ZFS, or try installing FreeNAS, it's free and setup in 10 minutes...
If you don't want a dedicated machine but still want to use ZFS you can do so in the XBMCBuntu release, just install ZFS-Fuse... that way you have all advantages of ZFS in your existing HTPC setup.

If you decided to google, also search for the term TLER, and you'll understand why hardware raid with cheap disks no longer is a good choice... At the first read error the disk gets kicked out of the array, will be found again and you are rebuilding the array for 72 hours, and again and again... This will probably not happen within the first few days, but very likely within a week or 2....

Note: The early "Green" models from Western Digital (EADS produced before november 2010 still have the TLER function.
The WD tool to enable/disable TLER does not work on the newer models.

Samsung/seagate also have TLER but call it different.... I think Hitachi still supports it but can not 100% confirm this...

Thanks Gollum. I recently bought a Zotac to connect to my DVD and the machine I had before with XBMC on it will now stream my media. The 4x 2TB drives I have are http://www.newegg.com/Product/Product.as...6822148681

Probably a poor choice, eh?

As for the controller, the LSI only does SATA II so I figured I'd do better to go onto the motherboard and get SATA III and I am running RAID 10 right now. Do you recommend at the very least that I get better drives or a better controller? Everything seems work fine now, except for a minor hiccup or two when I first start streaming a show or movie.

What about Windows 7 software RAID? That way if the mobo went bad, I wouldn't lose my data since as soon as I reinstalled Windows the array would be there.

the other major benefit of ZFS is you can move the pool (raid array) to any other computer with ZFS FS installed really easily - plus the bit rot detection, dedupe and compression (for all your pics, mp3s and normal files) that us ZFS converts go on about.

You mean physically move the drives? What if I want to install ZFS AND install enterprise level HD's for my server? Is there any way to mirror the data or would I have to just back up across the network to my main PC and then restore to the new ZFS raid?

yes - I mean you can simply unplug the drives and insert them into another computer (you should really do an 'export/import' command, but if your hardware has failed you can get away without doing that). Plus ZFS supports distributed replication/snapshots too.

Although I'd question the need for the enterprise level HD's unless you're looking at MTBF's etc.

edit: Snapshots and Clones of snapshots are very cool - I used it to share our music library; I snapshot'd all our music, made a clone that I shared to my wife's Mac/iTunes then she deleted all the crap she doesn't listen to and added her own stuff. Which shared the 50gb of music as two separate shares using only the original 50Gb of storage. Which I guess is another way of publishing a movie library for your kids with all teh adult stuff removed.

Basically ZFS gives you the same features of a Enterprise NetApp (I know that as I look after 7 NetApp filers with over 200Tb or storage)

What is MTBF?

So, you're saying keep my exact setup but by using ZFS I would be in much better shape to do what I'm doing?

What's the best way to archive all my data before switching filesystems?

mean time between failure - as others have posted, I have no idea what your setup is; ZFS as I've described it is really best suited to a dedicated server

you should head over here http://forum.xbmc.org/forumdisplay.php?fid=112