How many HD streams can a single drive take?

[autoboy]

I am upgrading to two HD R5000 tuners and I will have 2 HD tuners from my HDhomerun. That gives me 4 HD streams at once, plus I have two HD TVs and an extender for 6 HD steams and a SD stream.

I want to consolidate my 2 200GB recording drives, my 320GB drive, and my 100GB drive (JBOD) into a single 750GB drive. This will allow me to take the media server out of the garage and I can use my client PC as the server now that I don't need so many drives and analog PCI TV tuners. Will one drive with 64K clusters be able to handle this load?

[Protoman]

I have found this post, and thought it might help:

http://forums.sagetv.com/forums/show...ight=hd+speeds

I know there is another thread listing HDD Speeds, but can't find it at the moment.

Unfortunately, this might be a try and see scenario, as there are several variables that do come into play. Hard drive speed, network bandwidth (HDHomerun will use some for recording), and speed of computer.

Curiously, what are the specs of the system you are recording the HD to? I will be very interested to hear the results that you have with the 2 HD R5000 and HDHR.

Good Luck,
Protoman

[ybrew]

I'd put 2 500 gig drives in there just to be safe or is there simply not enough room in the case to do this?

[Protoman]

I was on NewEgg reading reviews for a new HTPC Mobo, and a posting by someone named Crunch is using SageTV and stated in his systems stats 2x HDHomeruns (AKA 4 QAM). Not sure how the details of his system specs, but it should be possible.

I did find this thread as well look at posting #3:
http://forums.sagetv.com/forums/show...87&postcount=3

I know i have seen a Thread asking "How many SD tuners" or something like that... I have a question.

How many HD tuners do people have, and how are they recording them?

Well, two questions I guess.

Thanks,
Protoman

[autoboy]

The PC that I will be running is:

Athlon 3200+ S754 @ 2.2Ghz & 1.1V
Biostar Tforce S754 mATX 6100 board w/100 mbit ethernet
ATI HD 2400pro (soon to be a 2600pro)
1GB ram
1 Seagate 320GB drive. OS 15GB partition, the rest will be recording space
Antec NSK2400 case
1 500-750GB drive to be purchased if it can handle the load

This is my current HD Client.

I want to replace my server:
Athon 3500+ S939
MSI Via ATX board w/gigabit ethernet
PCI 10/100 ethernet card for HDhomerun (uses 20-30% of bandwidth for 2 HD streams)
Nvidia 5200
2GB ram
2X 200GB
1X160GB
1X 320GB
2X pvr 150 analog tuners

I've never had problems with my setup so far but it is very rare that all recordings are going to one drive. It would be really really rare to have 6 HD streams going at once (4 recording and 2 playing) but could technically be possible. More likely, at high load there will be 2 HD streams recording, two SD streams recording, and 2 HD streams playing on the clients and there is a chance that would be spread out over both drives in the PC becasue I will have two drives. Maybe I could try this out with the extra 320GB drive frpm the server. That would give me 500GB to play with which would be fine for now. Soon as I get the RD5000's registered and modified I'll let you know how it goes. It would be nice to elimitate one more machine in my house.

Oh, and as far as playback goes, I'm counting on the HD 2400pro to offload the heavy work of HD playback. These HD streams are just disk writes anyways and shouldn't take too much from the processor.

[RobJ]

There is a very useful list of bandwidths, for common components, in this huge resource on building an HTPC: http://www.avsforum.com/avs-vb/showthread.php?t=710828.

Specifically, check out 'Appendix IV List of Bandwidths', near the bottom.

This is a very good and very long report/thread on AVS with a large section on motherboards, with specs and links to many reviews, mostly slanted to HTPC use. It is primarily Intel-based, but there is some support for AMD boards also. It starts with a lot of HTPC info, has a lot of educational material, lots of specs and reviews in relation to processors, memory, chipsets, hard drives, etc. It includes some recommendations and price data on Newegg. It's a little out-of-date, but that is understandable. There's no way a single person can keep a report of this magnitude up-to-date, and keep a job and family.

I only recently discovered this, others may already be familiar with it.

[autoboy]

Wow,

That is a great list and incredibly accurate. I have built many boxes and their info is spot on. Still, this does not help me. Bandwidth is easy to find but real world performance is another matter. 6 HD streams is only 120mbit at it's highest (20mbit maximum for broadcast HD) which is nothing compared to total disk drive bandwidth. However, a disk is a mechanical machine and cannot handle fragmentation inherent in recording and playing multiple video streams. I'm wondering if a single disk formated to 64K clusters can handle 6 HD streams on a totally fragmented disk.

I know that my 100mbit ethernet controllers can only handle 80mbit (4 HD streams) but that is ok because the HDhomerun and playback on two machines is only 4 streams. The other two streams are over USB and will not affect the ethernet.

[fas77]

I run

HdHomrun 2xHD (QAM)
Vbox cat eye 1xHD (OTA)
WinTV 1600 1xHD (OTA) 1xAnalog (cable)

All record to the same drive with 64k cluster.(IDE)
I can have all five recording and watch a HD show from
the same drive with no problems.

[autoboy]

Originally Posted by fas77

I run

HdHomrun 2xHD (QAM)
Vbox cat eye 1xHD (OTA)
WinTV 1600 1xHD (OTA) 1xAnalog (cable)

All record to the same drive with 64k cluster.(IDE)
I can have all five recording and watch a HD show from
the same drive with no problems.

Ok, perfect. So it sounds like it is possible. I think this is my plan then

[stevech]

I used IOMeter software to create independent threads in XP Pro to read SATA 2 with an AMD3800 with very fast memory.

With four threads reading the disk and discarding the data (not writing it or sending in on a LAN), it said the disk can sustain something like 40MB/sec. Mixed read and write in threads was about 20-30MB/sec.

What's an mpeg HD stream? 12Mbps on average? To avoid dropped frames and stuttering, I think one has to look at the peak demand, e.g., when a camera pans a busy scene.

[Protoman]

FYI,

I recently found out that SATA II drives are sometimes limited to only SATA I speeds via a jumper on the hard disk drive.

I have 4 SATA II Seagate 7200.10 drives, and after reading this I check one of the drives and sure enough it had a jumper that limited it to SATA I speeds. I also have an older WD (not sure if it is SATA I or II, but it did not have a jumper).

I removed the jumper and using HDTune I get something like 70 MB/sec average speed.

Thanks,
Protoman

[evilpenguin]

Originally Posted by Protoman

FYI,

I recently found out that SATA II drives are sometimes limited to only SATA I speeds via a jumper on the hard disk drive.

Do you have a link for that info?

[ke6guj]

Originally Posted by evilpenguin

Do you have a link for that info?

http://www.seagate.com/ww/v/index.js...00dd04090aRCRD

The jumper block adjacent to the SATA interface connector on SATA 300MB/s drives can be used to force the drive into SATA 150MB/s mode for use with older SATA controllers that only work with SATA 150MB/s drive

http://www.seagate.com/images/suppor...sata_block.gif
http://www.seagate.com/images/suppor...ta_jumpers.gif
see the notations to limit to or force 1.5gb or 150, that is SATA-1

[evilpenguin]

Originally Posted by ke6guj

http://www.seagate.com/ww/v/index.js...00dd04090aRCRD

http://www.seagate.com/images/suppor...sata_block.gif
http://www.seagate.com/images/suppor...ta_jumpers.gif
see the notations to limit to or force 1.5gb or 150, that is SATA-1

Thanks

[autoboy]

I removed the jumper and using HDTune I get something like 70 MB/sec average speed.

Yeah, that is average speed. That is not what it will do with fragmentation. This thing will have to sustain read and writes all over a fragmented disk without dropping anything.

Can someone try HD tune on their drives while 4 streams are recording to a single drive? I might be able to try it but I would have to disable my other drives for awhile.

[kevpriest]

I have an older rig for my server, using a 400 gig SATAI drive as my main recording drive. For awhile I had a Hauppauge 1600, Older Hauppauge 250, and a Hauppauge 950 set up to record 2 HD streams and 2 SD streams. One night several favorites hit (BSG, Heroes, and CSI NY, if I remember correctly) at the same time and the system tried to record 2 HDs and 1 SD at the same time (no playback occuring at the time). All three shows recorded, but all three had terrible skips and freezes for the length of the video. So, regardless of theory, on my system one disk couldn't take it. I pulled the 950 HD tuner and have done without until I figure out what to do to increase disk bandwidth. It's also possible there was a processor or memory bottleneck for me (as I said, it's an older system, an AMD 2500 with DDR RAM).

[stevech]

re the jumpers on the drives for 1.5 vs. 3.0Gbps

With IOMeter, I achieved 50-70MB/sec only with small transfer sizes; so I used very large ones and the speeds were expectedly reduced. I did so to ensure that the I/O could NOT be satisfied out of the Windows or disk-drive cache.

I just looked at my Seagate 500G drives; they have the 1.5Gb/s limit jumpers installed. Hmmm. Dare I remove them?

EDIT: With SATA-II, there is "automatic speed negotiation". If I have a very new mobo, I wonder if those jumpers are ignored?

[autoboy]

Originally Posted by kevpriest

I have an older rig for my server, using a 400 gig SATAI drive as my main recording drive. For awhile I had a Hauppauge 1600, Older Hauppauge 250, and a Hauppauge 950 set up to record 2 HD streams and 2 SD streams. One night several favorites hit (BSG, Heroes, and CSI NY, if I remember correctly) at the same time and the system tried to record 2 HDs and 1 SD at the same time (no playback occuring at the time). All three shows recorded, but all three had terrible skips and freezes for the length of the video. So, regardless of theory, on my system one disk couldn't take it. I pulled the 950 HD tuner and have done without until I figure out what to do to increase disk bandwidth. It's also possible there was a processor or memory bottleneck for me (as I said, it's an older system, an AMD 2500 with DDR RAM).

I don't think you ran into ram or processor limitations. I had 2 HD tuners and 2 analog tuners on a PII 350 with no problems. I moved to the Athlon for transcoding video. I did have problems with skipping video that I thought was my processor but it turns out my drive was failing and I replaced the drive and never had more problems. Check your drive with HDtune. I was getting severe dips to 1MB/s with my bad drive. (I with I could use a client for the transcode)

Will NCQ help with this application? Do all SATA3.0 drives support NCQ?