What RAID systems are you using

[Oats]

I'm currently in the middle of building a fileserver/NAS box out of an old computer. I just need to decide on a couple things like which OS I want to use (NasLite or FreeNAS) and if I want to buy a raid card or not. I already had the computer and four 200GB HDDs laying around. It will be used for DVDs and for weekly backups of important data from my other PCs (using XCopy batch files).

[Gaurav]

I had two 300G SATA drives setup as RAID0.

When i had first built my htpc 3 years ago, the RAID capability of the mobo was too cool for me to pass on and the recordings were not valuable enough to "waste" half the space on RAID1.

Just this past weekend i broke the array into two independent drives. Now i have the same space but i would only lose half the recordings if one of the drives burns out.

Haven't noticed any performance drop however there has been a slight increase in the peace of mind 8-).

just my 2 cents.

[stevech]

Originally Posted by Oats

I'm currently in the middle of building a fileserver/NAS box out of an old computer. I just need to decide on a couple things like which OS I want to use (NasLite or FreeNAS) and if I want to buy a raid card or not. I already had the computer and four 200GB HDDs laying around. It will be used for DVDs and for weekly backups of important data from my other PCs (using XCopy batch files).

From what I've read, Linux file systems and SMB overhead for windows clients yield a NAS that is much slower than a DIY NAS based on, yuck, WIndows XP. I may be wrong.

[dvd_maniac]

I found somebody local to me that wants to sell a Infrant ReadyNAS 600 and 4 500GB HHDs. 2 Hitatchi and 2 Maxtor for $899.00...
Does anybody here think it is worth the price or not?

[Oats]

Originally Posted by stevech

From what I've read, Linux file systems and SMB overhead for windows clients yield a NAS that is much slower than a DIY NAS based on, yuck, WIndows XP. I may be wrong.

I copied multiple DVDs from XP to FreeNas (I'm going to use NasLite which is faster than FreeNas) and I didn't notice any time difference compared to copying from XP to XP. I think the 100Mb network is the bottleneck. It still has more than enough bandwidth to play back ripped DVDs.

Also I like the idea of running the OS from a USB stick so that all the HDDs are used for storage only. If you use XP it will take almost 10GB of space. I guess thats not really a lot when you have close to 1TB of disk space, but I also don't have another copy of XP.

[_matt_]

Originally Posted by sundansx

You couldn't record 3 SD shows over gig ethernet to the ReadyNAS? That is ~10Mbit * 3 = 30Mbit? Something is wrong with your setup...does not compute. My Gig e-net does realtime transfers at a little over 200Mbit and that is not anywhere near optimal (PCI 32 slots, to non-raid drives)

With RAID 5 it's important to remember that writes are much slower than reads. This is because of the way RAID 5 works; when it needs to write something it must read from both the drive it's writing to and the parity drive and then write the data to the data drive and appropriate parity information to the parity drive, for reads all that needs to happen is to read the data from the data drive. Hardware RAID cards do as much as they can concurrently, but it is impossible to avoid slow down. This is frequently hidden with large buffers on the RAID card , however with a constant stream of data like a Sage recording the buffer becomes useless.

That said, I do realize that jlindborg did not state that his ReadyNAS was using RAID 5. I just didn't have a good explanation otherwise so I just pretended that he did.

[AngelofDeth]

RAID5 should be fast enough for 3 SD encodings being written. I only have two tuners, but mine isn't particular fast, and is quite old, and can handle 2 12Mbps/sec streams just fine. I'm sure 3 streams at a "normal" bit rate would be no problem.

[stevech]

Originally Posted by dvd_maniac

I found somebody local to me that wants to sell a Infrant ReadyNAS 600 and 4 500GB HHDs. 2 Hitatchi and 2 Maxtor for $899.00...
Does anybody here think it is worth the price or not?

Ouch.

You can pair a lot of $140 ea 500GB drives in RAID1 under XP for that price.
And - - I never buy used disks - mechanical, bearings, motors. Someone else used up much of the lifetime.

[stevech]

Originally Posted by AngelofDeth

RAID5 should be fast enough for 3 SD encodings being written. I only have two tuners, but mine isn't particular fast, and is quite old, and can handle 2 12Mbps/sec streams just fine. I'm sure 3 streams at a "normal" bit rate would be no problem.

Don't you have to allow for disk head seeks and the like due to streams coming off of the disks - to viewing clients?

[Fuzzy]

Originally Posted by erik

Did someone using SW RAID1 or 5 under Windows ever succesfully recover from a dead disk?
I tried RAID1 and Windows declared both dead.

I have never had a drive actually fail on me, but back when i was setting it all up, I first used a 3 drive array, and while it was running, unplugged one of the sata drives. It notified me of the failure, and I was able to rebuild the array using the fourth drive (which was IDE). The advantages I find with the software RAID, is that it is actually very portable. I can pull out these drives, and put them in my other system, and as long as that version of windows is also tweaked (or is running server 2k3) then it will automagically detect the array. No configuration required. If a drive controller fails, all it takes is a simple SATA or IDE controller.

The software RAID does use a bit more CPU, because it has to do all the XOR calculations in the CPU, but my server has plenty of time to spare, as all other processes (showanalyser, recompression, etc.) all run in IDLE priority.

As for preformance, I have never had any issues. The fact that the array is in my Sage Server, cuts down on the network traffic (as opposed to a NAS), as the only thing going oer the network is what I am currently watching. When I get a chance, I think I'll run a benchmark on the array, for comparison sake.

The cost of the software RAID is the real advantage, as the only money spent was on the drives. It even allowed me to use my older IDE 200GB drive as well.

[stevech]

Above your mentions of software RAID must be RAID5 or other striping RAID like RAID0. I'd think that RAID1 (mirroring) in could be at no penalty of two writes can be triggered simultaneously by the controller device. I think current motherboard controllers do this?

[Fuzzy]

Originally Posted by stevech

Above your mentions of software RAID must be RAID5 or other striping RAID like RAID0. I'd think that RAID1 (mirroring) in could be at no penalty of two writes can be triggered simultaneously by the controller device. I think current motherboard controllers do this?

I was discussing a RAID5 array. RAID-1 really doesn't serve much of a purpose for Sage Users (at least, not that I can see). As long as RAID5's slower write time does not impact your recordings, it still provides the redundancy, while holding more media than RAID-1 can. I was originally using a 2x200GB RAID-0 Array, which really provided great speed, but I wanted to use the storage for some more critical items (family pictures and stuff), so I wanted something a little safer. That's when I invested in two more 200GB drives, and set up a 4 drive RAID5 (only gave me 200GB more than before, with slower performance, but greater peace of mind) I haven't noticed a problem keeping up with recording, but I currently only have one HD source. If I end up getting an HDHomeRun, or other second/third HD source, I may need to rethink my decision. Don't really know what it can handl until I try it out. If I wanted more speed, I could go with a RAID50, but that would require some hardware, as I'm pretty sure Windows doesn't do this on it's own.

[jlindborg]

Originally Posted by sundansx

You couldn't record 3 SD shows over gig ethernet to the ReadyNAS? That is ~10Mbit * 3 = 30Mbit? Something is wrong with your setup...does not compute. My Gig e-net does realtime transfers at a little over 200Mbit and that is not anywhere near optimal (PCI 32 slots, to non-raid drives)

well, in theory, theory and practice should be the same - in practice they're not. I tested the write through using various measuring tools and the results were dandy all the way around, and yet it still didn't work smoth when I got three recordings going. Further it fragments the drives pretty bad since the NAS doesn't let you force formatting to 64k blocks - so this was another issue to be avoided.

Doesn't matter - record local and move works awsome and is not limiting at all. I'm not going to sweat the issue.

[stanger89]

The difference comes due to latency. The biggest bottleneck in storage systems today is latency, not raw throughput. Sequential reads are great on paper, but in practice they're not that applicable because in real-world situations latency is a large factor.

Storagereview has done at least one article on this. They debunk the idea that RAID-0 is a performance boost for normal applications, they show that most day-to-day applications are latency bound, not throughput bound.

Recording multiple shows is the same thing. Because you're reading/writing multiple files latency becomes the issue as the drive/system spends most of it's time seeking instead of writing. This is where the controller can really shine, through it's ability to intelligently queue read/write requests and buffer data to most efficiently write it to disk. I'd venture that it's latency where many a NAS suffers.

[mhassman]

For those people with cash, give raid 10 (or 0+1) a try.. doesn't have the write overhead of raid5.

I'm running 12 WD 250GB drives in raid 10 under a 3ware controller.. works great w/4 capture devices.. also worked fine with hd over firewire for almost a year until my hd-cable box stopped working - now just pixelated crap from firewire output.

[stanger89]

Originally Posted by mhassman

For those people with cash, give raid 10 (or 0+1) a try.. doesn't have the write overhead of raid5.

If you've got the cash, there's no reason not to go with RAID-5 and a good controller.

I'm running 12 WD 250GB drives in raid 10 under a 3ware controller.. works great w/4 capture devices.. also worked fine with hd over firewire for almost a year until my hd-cable box stopped working - now just pixelated crap from firewire output.

With 12 drives, really with any array of at least 4 on a good controller (3ware, Areca, etc) RAID-5 is going to be faster than RAID 10, even with the parity overhead. The reason being RAID-5 is striped over more drives. With 4 drives, the theoretical maximum transfer rate for RAID 10 is 2x the transfer rate of a single drive, with RAID 5 it's 3x. That's 50% greater theoretical max transfer rate. Now RAID-5 overhead eats some of that gap with 4 drives. But the gap widens with more drives, with 12, it's 11x for RAID-5 vs 6x for RAID-10, or 83% greater.

The following is very old but illustrates the point:
http://www.storagereview.com/article...ade7450_2.html

The single drives they tested were capable of ~30MB/s. The 3ware's scale basically linearly with RAID-0, ie 3 drives is ~90MB/s (just under).

With RAID-10, the 3ware's manage ~ 60MB/s (2x).

With RAID-5 the 3ware's manage nearly the theoretical 3x, almost 90MB/s.

Moral of the story, a good RAID card should make RAID-5 overhead moot.

Here's a more recent review, with Areca and new 3ware cards:
http://tweakers.net/reviews/557/19

From that you'll see the drives are capable of approx 60MB/s writes, and a 4 drive RAID-10 array on a 3ware or Areca is approx 120MB/s. Compare that to the RAID-5 results, the Areca with 4 drives in RAID-5 does ~180MB/s, and scales pretty linearly all the way through 6 drives. At which point it's hard to tell what happens but it looks like the bus may get saturated. I don't know what's up with the Highpoint or Raidcore at 6-8 drives as they seem to be going faster than theoretically possible.

[stevech]

RAID-1 seems to make sense to me, correct me if I'm wrong - as the lowest cost way to get fail-safe backup for large amounts of video files. It's a large price leap to RAID 5. Not about performance - but about affordable protection from inevitable drive failure. Seems to me like my drives last 2-3 years or so, of medium use. It's not if, it's when. I recently tossed my (dumb) collection of crashed-head drives; maybe 8 or so of them.

[Fuzzy]

Originally Posted by stevech

RAID-1 seems to make sense to me, correct me if I'm wrong - as the lowest cost way to get fail-safe backup for large amounts of video files. It's a large price leap to RAID 5. Not about performance - but about affordable protection from inevitable drive failure. Seems to me like my drives last 2-3 years or so, of medium use. It's not if, it's when. I recently tossed my (dumb) collection of crashed-head drives; maybe 8 or so of them.

Depends on what you consider 'lowest cost'. Dollars per MB, RAID 1 could be the most expensive, because you only get 1/2 of the Bytes you buy. Raid 5 gives you much more space to use, but requires 3 or more disks. (3 disks will give you 2/3 of the space, 4 disks -> 3/4, etc.) and RAID 5 still saves you from a single drive failure.

[stanger89]

It's a matter of scale. RAID, especially RAID-5, becomes increasingly logical as you increase the number of drives. If you've got one recording drive, it's pretty cheap and easy to get a second and use your "free" onboard RAID-1.

If you've got two drives, it's trickier, you could go RAID-1, but you could also go RAID-5 which depending on drives could be priced comporably. Good RAID cards are ~$300 for 4-port models, and that's about the price of a 750GB drive. So if you want redundancy for two drives, it's really a draw between a 4 drive RAID-1 array and a 3 drive RAID-5 array on a good controller. Of course if you go the RAID-5 route, you can always expand that array to 4 drives (50% more space) by adding a drive.

Anything beyond 2 "active" drives, and it's really hard to justify RAID-1. The extra cost in drives easilly outweighs the cost of a controller, especially with large drives.