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Am i expecting too much from my system?

G

Grasbak

macrumors 6502
Original poster
Jan 17, 2006
434
16
UK
I recently upgraded my iMac G5 (iSight) to 2.5gb ram and added a WD Mybook 500gb firewire HDD. The idea was to use the external to record my eyetv programs onto - which would reduce the Macs HDD usage, so, if eyetv is recording in the background, I can get on with other things more efficiently. However, I notice that while recording (to the external firewire), if I play a song through iTunes (on the mac HDD), it skips. When i am not recording, it stops skipping.

Am I execting too much from my iMac? Or is something wrong?
 
Grasbak said:
I recently upgraded my iMac G5 (iSight) to 2.5gb ram and added a WD Mybook 500gb firewire HDD. The idea was to use the external to record my eyetv programs onto - which would reduce the Macs HDD usage, so, if eyetv is recording in the background, I can get on with other things more efficiently. However, I notice that while recording (to the external firewire), if I play a song through iTunes (on the mac HDD), it skips. When i am not recording, it stops skipping.

Am I execting too much from my iMac? Or is something wrong?
Click to expand...

Thats quite a lot your expecting form a single core CPU, if it is the eyetv that uses software encoding then theres your problem, open up activity monitor and see how were your cpu resorces are being used.
 
Thanks for reply - although I guess on one hand its dissapointing, on the other, its some ammo for getting a new mac :D

So its more of a CPU thing than the access to the HDDs. Why cant iTunes just buffer a bit longer or something to compensate?
 
Testing as I type

I am recording to eyeTV (on the firewire drive) - listening to iTunes (which is skipping) - I also have safari open, mail, ical, address book, word, isync, activity monitor - also 10 widgets on dashboard

CPU usage is fluctuating a lot, there are 252 threads and 72 processes running but generally speaking there is 50% of cpu idle at any time. I still have 1gb RAM free.

I have stopped recording on eyetv and the skipping stops straight away although eyetv still uses 18threads - the total threads still at 250, processes @72....

Why is iTunes skipping??
 
does eyeTV use a scratch disk? Is it set to your internal HD that iTunes is accessing?
Click to expand...

erm- I am not sure what a scratch disc is, but I have set eyetv to use the firewire drive, it then stores all recordings there, records directly to it - and the live buffer.
 
Have you tried recording to the internal disk? does it still skip then?

are you recording in HD or SD?

what's the data written a second as reported by activity monitor?
 
Grasbak said:
Can anyone offer any further advice?

Thanks
Click to expand...
I have one of the new aluminum 2.4GHz iMacs. Although with EyeTV running, I haven't had any skips or other system slowdowns, EyeTV still uses 50% CPU sometimes when it's playing-back (when just recording, it uses near no CPU on mine), which is pretty huge. I think you might want to consider upgrading...
 
I reckon it depends on a few factors:

  • If the Elgato/Miglia hardware you're using relies on your Mac's processor, rather than it's own, that'll slow you down. Could be related to the third point below as well.
  • You're recording on to an external drive, but the information still has to pass from the device, through the Mac's FireWire bus, to the external drive. I guess you're using FW400. That could be a choke point - try recording to your internal drive as someone else suggested, see if you get the same issues.
  • Are you recording analogue or digital TV? Digital TV signals are already compressed so they shouldn't cause as much hassle as recording analogue which are uncompressed and require a lot of processing power dedicated to them.
I used to have an Elgato MiniTV which used USB on my iMac CoreDuo - recording analogue TV meant the system was pretty much useless for anything else.

Another possible solution (instead of upgrading your Mac) would be to upgrade your Elgato/Miglia hardware. The new Elgato EyeTV 250 Plus looks like a good all round option, with on-board hardware processing which will take the load off your Mac.
 
Thanks for suggestions - I will have a closer look tonight when I get back from work.
 
Returning to this thread as noticed something else today.

I am transferring 2x1gb files from the firewire (400) drive across to a usb 2.0 memory stick. It is really slowing my system down. Is this right?
 
FJ218700 said:
^^ in activity monitor, should be the finder that is hogging the CPU during such a transfer. It's normal for me on my older systems.
Click to expand...

there really shouldnt be any massive slow down. the music that you are playing is from the internal or external harddrive ???? if it is on the external then that will be why it is slowing down the music (to many requests on different parts on the hard disk)
 
I don't think his/her music is slowing down, just overall system responsiveness. Again, I also get this on my G4's when transferring large amounts of data in the background.
 
Just to clarify - the general issue is that when the firewire drive is running it significantly affects the rest of the system.

things i had noticed

1. I assumed if I record eyetv to the firewire it frees up the internal hdd to play itunes etc - but itunes skips if the firewire drive is operating.

2. when transferring 2x1gb files from the firewire drive to a usb flash drive my system response way very slow - moving windows round was very jerky for example.

One of the reasons for buying the drive (the main being space!) was to ease the pressure on the internal hdd. I often am recording eyetv progs in the background whilst working on other stuff and perhaps listening to music. I just wanted to be sure that the issues I have noticed are to be expected.

Seems like its more to do with pressure on the CPU than anything else.
 
Update! Drive no longer on desktop!

Ok - something new happened now.

Woke mac up from sleep - message on screen says about device removal - i havent removed it - it has been attached since i bought it (2 months ago)

Tried restarting mac - unlpugged cable - turned drive off and on etc. Doesnt show up in disk utility.....

What do I do? Fans on the drive are working - it seems to be 'alive'

Thanks
 
working again....

ok, so i unplugged the drive, came back a few hours later and plugged in again. This time it mounts!

Somewhat frustrating as I have no idea why.
 
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