On 12/18/2012 02:51 AM, Andrius Narbutas wrote:
On 2012.12.18 05:41, Robert Hancock wrote:
My first thought would be that a power problem is a possibility. These
kinds of setups with multiple HDs in a RAID setup are known to cause
these issues in some cases if the PSU isn't adequate.
I do not think PSU is a problem, because:
1) All hard disks combined draw less energy than loaded CPU, even at
heavy load (from HDD datasheet: "Read/Write: 6.80 Watts; Idle 6.10
Watts" - difference is 0.7W per HDD, so < 3W combined, CPU draws ~40W
when loaded, compared to idle). Loading CPU/RAM to max does not crash
system at all
The CPU has a voltage regulator in front of it which can compensate for
dips in the input voltage. The disks don't. The wattage figures don't
necessarily account for short-duration power draw peaks. And depending
on how the drives are hooked up, especially if they are all on one
cable, they can potentially see a problematic voltage drop.
2) I'm planning power supplies at 2x needed power (you know, all those
"Chinese Watt" system is unreliable). Anyway, should be more than enough
for whole system (and CPU is almost at idle when creating filesystem, so
load on PSU is very low - should be < 70W - that's almost nothing on
560W PSU, even counting "Chinese Watt" coefficient)
3) If PSU is fault - why it fails at exact the same place? Most of
hardware failures have some "random" factor - you get segfaults at
random places from faulty RAM, crashes from dying PSU when doing random
tasks... But now it fails at exactly the same place (when using the same
kernel)
4) Let's say PSU is faulty. Then how comes, that with 3.6.10 kernel i
still have control over system (when it crashes) - so only disk
subsystem fails? Because it has only one 12V rail - you cannot
disconnect disks from system, without killing motherboard power too. But
after crash i still can do `ssh root@deadhost 'echo b >
/proc/sysrq-trigger'` - so system is alive and working well (just disks
are dead)
I could imagine that motherboard itself is faulty (well, interesting
anyway - why it fails only on heavy I/O load), so i will try to get
Windows Server installed to check if that will work.
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