Issues with disk access

[Mahoney]

I've got a couple of 300MB SATA disks, just setup as separate disks. I think I'm having serious issues when there is too much concurrent access; tonight I was trying to record two shows whilst watching one of them, and both recordings are seriously screwed up.

The server has 512MB and an XP 3000+ processor. So I'm guessing the issue is the disk, rather than anything else? Sound right?

Other possibility is that it's the bus on the motherboard, which seems a bit unreliable; occasionally after a reboot it doesn't recognise the drives.

I'm contemplating getting a RAID card as the solution, but I'd like to be certain that it will actually cure the problem! Any thoughts?

[paulbeers]

I wouldn't guess the problem is the processor or memory if this is only being used as a Sage Server. I have an Athlon64 3000+ w/ only 512 mb of ram and no problems. I would guess it is either the drives themselves or the controller. I have 2 - 200GB PATA drives set up as seperate disks just like you, and I have no problem recording 3 shows and watching one. Are you recording/watching HDTV or SDTV? That would make some difference. If you are just doing SDTV then you shouldn't have any problems, but recording multiple HDTV and watching an HDTV would be a little tough on your drives. SDTV though is only about a megabyte per second: 3.2 GB per hour = 3276.8 MB per hour / 60 minutes / 60 seconds = .910222 MB per minute on the best quality setting. Your SATA drives should be easily able to 50 MB/s (yes I realise there is a big pentalty for non-consectutive read and writes caused by recording and watching multiple shows at at a time, but even at a 50% pentalty that should still leave you 25 MB/S). It is either your drives or the motherboard itself. If you can get a cheap SATA PCI card, I would give that a try to figure out if it is your mobo or the drives.

EDIT: Even with HDTV, I can't see that being the problem: 9GB per hour * 1024 MB per GB / 60 minutes per hour / 60 seconds per minute = 2.56 MB/Sec so even with recording two and watching 1, that is only a total bandwidth of 7.68 MB/Sec.

[Opus4]

Are the disks formatted using 64K cluster sizes?

- Andy

[Mahoney]

I believe they are 64K clusters, though I'm struggling to prove that now. Looking inside I'#d forgotten that I have actually installed a SATA card rather than runnign them off the machine's bus, so I might move back to the machine's ports to see if that improves things.

Honestly, after more than 15 months now I am regretting ever getting involved with Sage. It's a lovely idea, but between the hassles of getting a UK XML feed (it's OK, but not great...), getting reliable recording (current issue), getting decent quality playback, getting a client that doesn;t crash on a regular basis when stoppig playback (another current issue)... I should just have got Sky+. I hate to think how much money and time and frustration I'd have saved, and actually had a reliable system. Might actually watch a bit of TV. No way would I ever advise anyone to go down this route.

[Opus4]

Originally Posted by Mahoney

I believe they are 64K clusters, though I'm struggling to prove that now.

You can open a command prompt & run chkdsk for the drive(s) in question. It will tell you the number of "bytes in each allocation unit."

- Andy

[Mahoney]

Thanks, Opus4. Yes, they are 64K clusters. Is there a diagnostic tool that can check disk read/write capabilities for a system?

[Mahoney]

Hmm. Currently recording three things at once (all SD) and playing back two of them and no problems it seems. So I wonder what caused the cockup before?

I've stopped the hard drives being switched off after inactivity. Perhaps that was kicking in inorrectly in mid record or something.

[Mahoney]

THanks, paulbeers, too - sorry, should have acknowledged your help earlier.

[GKusnick]

The performance monitor applet that comes with Windows has a number of settings for monitoring disk utilization, if that's what you're looking for.

If you're wondering whether the disks themselves are malfunctioning, the disk manufacturer should have diagnostic tools available for download on their website.

That said, disk performance is generally the last thing I'd suspect in a case like this. Unless the drives and/or controller are defective, you shouldn't be coming anywhere near your disk bandwidth limit.

You haven't said much about the rest of your setup (at least not in this thread) but in your shoes I'd be checking the tuners for IRQ conflicts and making sure I had the most reliable (not necessarily the latest) available tuner drivers.

[Mahoney]

Spoke too soon. One of the playbacks just failed, and the other is glitchy.

The tuners have been working for 6 months plus now. I don't often try and record two things at once, I guess - I'm not the most avid TV watcher by any means.

I have a server with a PVR500 and a Terratec Cinergy 2400i dual DVB-T tuner. I have a set top box going into one of the PVR500's inputs and UK freeview into the Terratec. I used Anders' DVB plug-in to control theTerratec. All running on a K8n Neo 4 motherboard, Athlon XP 3000+ with 512MB. OS is Server 2003 with DirectX installed.

Playback is by a GeForce 6150 running an Athlon Xp 3000+ with 512MB RAM and XP Home, using PureVideo VMR9 and FSE on one machine (using client) and another machine using placeshifter.

What I'm seeing is consistent with trying to interpret and play back partially corrupt MPEG2 streams, I would say; Sage gets very confused at times with how long the file is and skips around or stops playing back, or in good cases just glitches occasionally.

[Mark SS]

How fragmented are the drives?

[Mahoney]

14% total, 28% files. I'll defrag tonight.

SBDARecorder crashed just now, which is the first time it's done that. Something odd going on.

Need a full time systems person just to keep this setup running. I was mad ever to start it. Even if SageTV were utterly perfect, computer hardware, drivers and OSs are far too fallible for it ever to be other than a hassle.

[Mark SS]

SBDARecorder has always crashed periodically for me, maybe once or twice a month. Always seems to occur on a channel change but I've never tracked down exactly when or for what channels.

Aside from SBDARecorder Sage has been pretty stable for me, its my meddling that seems to cause the problems in the pursuit of better PQ and so on. The benefits of a 5 tuner system, streaming around the house and Placeshifting while I'm working abroad keep me dedicated, so far.

Regarding the drives problem, I have 2x300gb drives mirrored using the built in features of the NF4 motherboard. Not noticed any drive related problems despite recording 4 items at once and playing back 2 (1 via server, 1 via Placeshifter). Do have a problem with what I suspect is one of the drives being knackered as it keeps dropping out of the array but thats another story.

[Polypro]

In Device Manager, for your IDE controller, are they showing SATA 3.0, 1.5, or UDMA 5/6...or are they in PIO mode? Also, if SATA, I've had the first gen power connectors lose the connection...not fall off, but just not make contact correctly in the confines of an HTPC case. Both of mine are now masking taped to the bottom of the case, exerting downward pressure on the power connector. I had the exact same unrecognized drives in BIOS problem because of that.



P

[paulbeers]

I am assuming you are using all PCI cards. Could you possibly have an IRQ issue between the SATA controller card and the PVR500? What about bandwidth? You might be maxing out your PCI bandwidth which could be causing a problem? Just some thoughts. If I were you, I would use the onboard SATA if possible.

[Mark SS]

Originally Posted by Polypro

Also, if SATA, I've had the first gen power connectors lose the connection...not fall off, but just not make contact correctly in the confines of an HTPC case. Both of mine are now masking taped to the bottom of the case, exerting downward pressure on the power connector. I had the exact same unrecognized drives in BIOS problem because of that.

When I installed the drives I thought the power connectors seemed a bit flimsy, especially compared to IDE. Thanks for the tip, I'll give that a shot.

[Mahoney]

Just wanted to apologise for my whinge on this thread. I think it was my fault - using an old PCI based SATA interface card rather than the onboard SATA. Shifted the drives back to the onboard SATA and so far no recording issues. I guess the PCI bus wasn't up to the bandwidth.

There are still days I regret doing something that requires me to do so much under the hood, but this was definitely entirely out of Sage's control!

[paulbeers]

Hehehe, I don't think any apologies are necessary. We have all been there. We have all done things we lived to regret later on (and not necessarily just our computers!)

[blade]

Originally Posted by Mahoney

Just wanted to apologise for my whinge on this thread. I think it was my fault - using an old PCI based SATA interface card rather than the onboard SATA. Shifted the drives back to the onboard SATA and so far no recording issues. I guess the PCI bus wasn't up to the bandwidth.

I think a lot of the really odd problems people run into are hardware related and they just don't realize it.