Sunday, 29 July 2012

Day 5 - Busiest day in the first week?

Despite being a Sunday, it's not a day of rest for Olympians as we have record numbers of sports (24), satellite channels (24), satellite recording slots (58) and recording time (226 hours) to deal with today. To cope with this, I'll be splitting equestrianism (split at 13:25), sailing (15:00) and tennis (15:45 or 16:05) into two recordings because they're all crazily over 6 hours each. I may do each split a little earlier if 90% SSD usage on pc2 is reached before then and if things get really tight, I'll look at splitting the football at 14:30 too (5 hours 20 mins for two fixed-length matches that last about 2 hours each! It's totally criminal the BBC don't have those in 2 slots with at least an hour gap between the slots).

Other PC adjustments include suspending at 1.15am, 1.30am or 1.45am (whenever the machine is idle and has no-one logged into it) with a wakeup 15 mins before the first event in the morning (though I'll power it up an hour before the first event anyway to do my system checks). On both pc1 and pc2, I've removed transmedia's verify pass and also reduced the check interval for files to copy from SSD->HDD from 5 minutes to 3 minutes (two successive checks have to have the same timestamp and filesize for the file to be copied).

Each day, I check all the tuners are reporting 100% quality and I also check whether duff tuners 2 and 4 on pc1 are working. This morning saw a bit of life from tuner 2 - the transponders reported OK for the first time since the fault, so I've decided to try and use tuner 2 today (handball is recording on it as I speak). Tuner 2 is now also recording the dreaded 7 hour equestrian slot.

Now tuner 2 in pc1 is operational, I've removed the recording of Freeview 304 (HD version of 301) again and this has balanced the SSD usage between pc1 and pc2. The extra tuner available in pc2 (used for recording 4 HD channels) is counteracted by recording 2 HD and 3 SD terrestrial channels on pc1.

One thing I can look at is possibly doubling up now on one or two recordings. I'm experimenting with the 12:00 tennis session on both pc1 and pc2 since I'll be splitting both at 16:05 and can do the split a minute apart to avoid losing any video. Yes, it did occur to me that you might be able to record the same slot on the same PC and tuner twice, but tvheadend won't let you do that (presumably once the process has the tuner stream for the initial recording, it can't access that stream a second time).

So far so good with balancing the SSD space and tuners today, but it struck me that after 14:40, there's only a couple of recordings finishing until 16:25 (so only a little SSD space can be freed up except for my splits of course), but loads of stuff - 9 recordings! - fires up between 14:20-14:55 that accelerates the SSD usage from as low as 30% right up to 80% or beyond an hour or two later (I'm hoping my splits will keep it below 80%). I suspect we'll see this pattern throughout the Olympics, because it certainly happened yesterday as well.

The good news is that I got through the peak recording period with a maximum of 83% of the SSD space used on either PC. There are less simultaneous sessions in the evening than in the afternoon, so there's no issue with space for the rest of the day. I still won't be able to watch my recording of today's F1 GP until about 20:30 tonight, because all evening sessions will have started by then and they can be run unattended.

Another day over and I've written a script to show me the active recordings and the space they use on the SSD (and the free space left on the SSD), plus any that have finished and not yet copied to HDD. It's just for reassurance that the "recording blobs" in tvendend match up with what's going on w.r.t. the filestore.

 Day 5 recording size: 1192GB (a new record) - grand total so far: 2973GB (2.9TB)

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