HD Speed problems. Problably IRQ related.

Phantazm · n00b Joined: 29 Jan 2005 Posts: 5 Location: SE

Hi.

I got this huge problem. I Currently have 3 Gigabit NICs and 10 maxtor 200gb drives in a raid 5.

8 Drives are connected to 2 PCI Promise ATA133. 2 connected to IDE-B and HDA for bot is on IDE-A

It seems like the drives or the PCI cards have problems handeling the load. If i copy something to HDA over gigabit i get about 40mb/s.
To the drives that is in the raid i get 30-50mb/s but many strange freezes.

Copying from md0 to hda directly gives about 120mb/s and it also freezes from time to time. HDA to HDA works without any freezes.

Before i had a configuration of 6 disks using only one pci ata133 card and that worked like a charm. Beenn chaning around the pci slots to make sure that the cards arent sharing IRQ.

im using kernel 2.6.10-r6 and i dont think this is a raid issue.

Anyone got some tips and tricks?

NeddySeagoon · Posted: Sat Jan 29, 2005 10:55 am Post subject:

Phantazm,

If your PCI bus is 32bit 33MHz, its hugely overlaoded. That gets you a theoretical bandwith of 133 Mb/sec, so pratical values of 40Mb/s for moving data over the bus twice is quite good (80Mb/s actually used).

Even a 64bit 66MHz bus (4x the bandwith) will struggle to keep that lot busy.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Phantazm · n00b Joined: 29 Jan 2005 Posts: 5 Location: SE

So basicly it can be unsolvable?

Damn that sucks. It's i pretty loaded to have 2 gigabit nics and 2 PIC controller cards holding 8 disks. But all the freezes makes me go crazy.

Worked like a charm with 4 disks.

Thanx for your answer.

NeddySeagoon · Posted: Sat Jan 29, 2005 12:55 pm Post subject:

Phantazm,

It should not hang up, just be very slow because of the PCI high bus utilisation. Shared interrupts should be OK too.
Most motherboard only allocate 4 interrupts for the PCI bus and even then some are shared with onboard items.

I suppose that if the PCI arbitration is not 'round robin' so everythiing gets a chance, some lower priority devices may never get the PCI bus. I would need to check the PCI spec to see what sort of arbitration scheme it uses and if it can be changed.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Phantazm · n00b Joined: 29 Jan 2005 Posts: 5 Location: SE

Well its a MSI Neo 2 with p4 2.8HT

irq