dropped frames on output of HD from kona 2

[Bob Zelin]

run AJA Kona system test again – observe the read and write time – do you see hesitation in the test while running, or is it smooth, with consistant write and read speeds. Look at your SCSI array activity lights while running. Are one of the drives “hanging up” (is one of the activity lights getting “stuck” while the others are flashing) ?

Even though you are seeing 230mb/sec speeds, drop frame problems are most often associated to problems with the drive array. If you have one drive failing in the array, it will be difficult to diagnose these issues, and that is why you should observer AJA Kona System Test – look at the graph, look at the “smoothness” or consistancy of the write and read speeds. If it’s hanging up (even for a moment) while it is writing files (and write 4Gig files, not 128mb files) – this is like getting the drop frame error from FCP. I know that you don’t want to hear this (because your project is on your SATA array), but that is most likely where the problem is. This is NOT a RAM issue.

Bob Zelin

[Richard O]

Hi Bob

Thank you very much for this advice. I have now run the test and looked at the graph, and your suspicions are correct. The read speed sits at around 280, and the write at around 225, but there are around a dozen big spikes on both read and write where it drops down to under 75. I ran the test twice and got similar (but not identical) results.

I think this sound like the cause of my woes.

In your experience, is this problem solved only by reformatting? I have heard that defragging of SCSI arrays is a dodgy affair. I can’t afford to lose this media, of which there’s about 2.1TB. I flagged this problem up to the supplier of the hardware back in February, and then in May, airing my suspicions that it may be a drive problem. They never advised me to run this test though (they did advise that I trash my preferences. Then that I defrag. Then, a week later, that I definitely DO NOT defrag! It was at this point I began to lose faith in them….).

So, thanks for your advice so far – its better than I’ve got from the supplier! Any further recommendations will be very gratefully received.
regards
Richard.

[Jeremy Garchow]

Make sure everything is rendered and mix down your audio. You can also turn off the ‘mirror on playback’ for output and that should get you some more rt performance for output. You said you have 50GB free out of how much space? SOunds like your drives are getting pretty full and might be time to do some house cleaning and reformatting.

Jeremy

[Bob Zelin]

Jeremy gives good advice, and certainly reformatting would not hurt to see if it’s just data corruption. But the last 2 times I had problems with XServe RAID’s, the first time, the firmware was not updated, and the cache flushing was not disabled in RAID admin, and the second time I had a problem, I had a flakey drive. I was fortunate enough to see the “blue LED” get stuck in the on position. Shane from ProMax correctly advised me to yank out the drive (it defaults to RAID 0 when you do this), and everything started to work.

I can assure you that if you do not have the current firmware version on your XServe RAID, and disable cache flushing, you will have drive perforamnce issues.

Bob Zelin

[Richard O]

Thanks again. I’ve arranged for another RAID to be loaned to us, so I can copy all of the media across and then format and check the original array. I’ll make sure they look at the cache and firmware issues.
regards
Richard

[Bob Zelin]

Make sure that “they” know what they are doing, and know how to go into RAID Admin.

Bob Zelin

[Richard O]

Hi Bob

The supplier’s solution was to send new cables and terminator and driver software. This has made no difference! Thought you’d be interested to see their response regarding the ‘spiking’ data rates on the Kona drive:

“With regards to the diskwhack test, it is only the write/read figures on the
main window that should be taken in account, as the graph will show those
kinds of results with any drive or free space. The main screen shows the
read/write to be above 200MB/s, which is fine for HD & indicated no problem
with the drive.”

I’m not sure how that logic works, because surely any point the drive dips below 100mb/sec, it is unable to feed HD at the full frame rate? That seems to make sense to me.

They also suggested that my free disk space may be an issue – i’m down to about 5%. I’m trying to free up some more now, and see if it helps.

all the best
Richard.

[Jeremy Garchow]

[Richard O] “because surely any point the drive dips below 100mb/sec, it is unable to feed HD at the full frame rate?”

Not really, that’s what cache is for. The spikes are okay they are only for a fraction of a second. Sustained speed is what you need. Clear off some space and you will be fine. Your drives are full and can’t handle the data you are trying to throw at it.

Jeremy

[Richard O]

Aha – thanks for the quick reply. I’m off for a thorough trashing now.
all the best
Richard.

[Gary Adcock]

[Richard O] “They also suggested that my free disk space may be an issue – i’m down to about 5%. I’m trying to free up some more now, and see if it helps.”

WHOA
the problem here is between the floor and the keyboard

having less than 5% of your total storage space available on any NLE system is an incredibly bad idea, in addition to having multiple nested sequences that may or may not be fully rendered in the background.

Render out the project to a self-contained movie file and then print to tape.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows