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Luke: Decklink SP and G4 dual 1.2???
I’m trying to set up an older G4 as a mobile edit station with an internal SATA raid. Dual 1.2 with FirmTek 1S2 Sata controller and 2 Maxtor Diamond Max 10 7200rpm drives. I’m encountering a problem that I guess has plagued others before. I found this in a pre vious post
“I built a 2-disk SATA RAID 0 for a dual G4 1.25 DeckLink SP system. We’re getting dissapointing transfer rates from the RAID as long as the DL card is in the computer. Remove it and the RAID performs much faster and as expected. ”
Without the Decklink SP, I get read and write times right around 100MB per second. With the decklink SP, the read times drop to 50MB per second and the write times drop to 30MB/sec or less. Doesn’t matter which PCI slot the various cards are in. Any ideas on fixing this?
Luke??
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2 Replies
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Hi Mark,
Sorry this hasn’t been answered before. I’ve never tried a SATA card in a G4 but have received various reports from customers and they are consistently poor. I would recommend you use a U160 SCSI or FC (33 MHZ PCI) solution. If you have already invested in SATA disks, you could use a JBOD which takes SATA disks but uses a SCSI connection to the chassis. You could also use a FC chassis but it will be more expensive.
The 33 MHz PCI bus in your G4 is a shared bus and all PCI cards have to take turns requesting access to the bus. The reason you are having this problem with the SATA card is that it isn’t polling the PCI bus regularly enough. The DeckLink card polls the PCI bus very frequently which means that when the SATA card wants access to the bus, the DeckLink card might already be using it. The solution is for the SATA card to poll the PCI bus more frequently and the manufacturer of the card might have a firmware update which helps with this.
I think SATA is a great technology for use with G5’s and independant PCI-X buses but it doesn’t work well in G4’s if you also need to use other demanding PCI cards. Video is about as demanding as it gets and that’s why you’re seeing a problem.
It’s also possible to exhaust the capacity of the 33 MHz PCI bus. I previously tried running three cards simultaneously in the G4. I tried an ATTO UL3D SCSI card with an Apple Fibre Channel PCI card and a DeckLink card. Both disk arrays suffered in performance and I found I could only run one at a time at full speed. The alternative was to remove the DeckLink card. So this was a case of exceeding the capacity of the PCI bus.
I have received similar reports from customers attempting to run a FireWire 800 card, an ATTO UL3D card and a DeckLink card simultaneously. It just doesn’t work well unless you remove one of the 3 cards.
In your case you are just running 2 cards so I would suggest checking with the SATA card manufacturer for a firmware update. Failing that, I would suggest using an ATTO UL3D or UL3S SCSI card. This will provide you with U160 SCSI speed which is perfect for standard definition in a G4.
If you have any further questions, I suggest you start a new thread otherwise it might not be noticed.
Regards,
Luke Maslen
Blackmagic Design -
Mark and Luke,
A better, less expensive 2-drive array for the G4 and a DL card is to use ATA drives and not SATA. The ATA bus doesn’t seem to be affected by the DL card polling. I’ve got two 250GB Hitachi ATA drives striped on the ATA100 bus and the read/write performance is 100MB empty and about 90MB full. The only downside is the Mac system drive has to be put on the ATA66 bus but it’s really not that bad.
Franklin
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