HDTV and Hard Drives

[paulbeers]

While I don't believe RAID 0 helps in a desktop enviroment, from a Sage Server standpoint, it could based on this article:

http://tweakers.net/reviews/515

My only thought is that if you are writting 3 or 4 streams at a time, it is going to be a non-sequencial read/write, so again RAID 0 may not help. If you choose to go to a RAID 0, be sure not to put your OS on it (as RAID 0 increases your chance of failure).

[jkohn]

All I can tell you is what works for me. OS, Apps, and pagefile are on a completely separate drive so the RAID 0 is just for recordings. But I can tell you I get better performance using a single RAID-0 drive than I did with two separate drives. Part of the problem is there's no way to make Sage load-balance between the drives. Yes I know you can tie a tuner to a specific folder but that breaks down if you have more tuners than hard drives. Plus file management is easier this way. And despite the supposed great risk of failure, I've never lost a RAID-0 array. Granted I would never put irreplaceable files on RAID-0, but we're talking about TV shows here. It would hardly be the end of the world if something did happen.

[phelme]

ignore this and read the next message below:

I'll pick up another drive and see if writing the SD streams to their own drive and each HD stream to its own makes a difference. if not, I'll look at RAID 0.

I think I'm running into the same problem that others who have tried NAS lite boxes have, can't sustain 40-45 Mbps network loads coming in as 4 streams and writing it all to disk as 4 files at the same time on the same bus. at least my nForce4 board can't.

[phelme]

I figured out my problem after realizing the HDHomeRun works off UDP and I should be looking at network rather than disk solutions. discovered others were having dropped packet issues and found this thread: http://forums.sagetv.com/forums/show...475#post130475

there is a feature of many NIC's called "checksum offload" and disabling it fixed it! I think the CPU is a bit more busy now, but still has plenty of cycles left to handle everything.

note: you may need to disable "segmentation offload" as well.

[jkohn]

That's good news. The NForce4 NIC is pretty lame, I'm not using that chipset in my Sage Server or Client but do have it in my workstation. I found that using the secondary GB NIC instead of the NForce4 gives me better performance.

[rickgillyon]

Originally Posted by jkohn

But I can tell you I get better performance using a single RAID-0 drive than I did with two separate drives. Part of the problem is there's no way to make Sage load-balance between the drives.

Sage does load-balance in its own way, but only if the two recordings are concurrent and free space on the drives in more-or-less equal...

Since I dropped RAID-0 I've dropped an awful lot more frames in recordings, RAID-0 is undoubtedly faster than two drives. But it was a bitch rescuing the recordings off my RAID-0 with the dodgy HDD. My conclusion? I'm not really sure, RAID-0 is great for video capture but is a pain when it screws up. Sure, not the end of the world but that documentary from last year seems more important when you're about to lose it.

[jkohn]

Originally Posted by rickgillyon

Since I dropped RAID-0 I've dropped an awful lot more frames in recordings, RAID-0 is undoubtedly faster than two drives. But it was a bitch rescuing the recordings off my RAID-0 with the dodgy HDD. My conclusion? I'm not really sure, RAID-0 is great for video capture but is a pain when it screws up. Sure, not the end of the world but that documentary from last year seems more important when you're about to lose it.

I guess it depends on your viewing habits. I pretty much just timeshift, deleting things immediately after watching them. So it's not like I have an archive of saved recordings going back months or years. And even if I lost an recent episode of my favorite show I can most likely find a copy through alternate sources. So for me the (very slight IMHO) risk is worth for increase performance and reliabilty (reliability in the sense of dropout-free recordings).

[phelme]

turns out my corrupted file problem was not disk, nor NIC related. I (unfortunately) have 3 switches between the server and the HDHR and the cascaded 10/100 switches couldn't handle all the streams to my server. now that I have gigabit switches instead things are fine. thankfully, gigabit switches are now cheap.

oh and if you ever need to find out the bandwidth of your net I recommend iperf.