On Fri, Oct 03, 2014 at 02:19:55PM -0400, David A. De Graaf wrote:
On Fri, Oct 03, 2014 at 04:01:30AM +0930, Tim wrote:
Allegedly, on or about 02 October 2014, Chris Murphy sent:
Cables are often the source of weird problems. Specifically it's the
connectors that are flakey, not the cable portion itself.
Though, if you savagely bend SATA leads, the way some of them are
supplied in a flattened up zig-zag style, with a rubber band around
them, you can mess up the data transmission.
Some quick feedback: It's now apparent that the cables or SATA
sockets have nothing to do with my problem. The finger of guilt
now seems to point to the RAM sticks. However, experiments are
slow. More later.
After weeks of experimentation it's clear that my machine crashes have
nothing to do with the SATA connections or the harddrives.
They are caused by a too-small swap space!
Zero is OK; large is OK; but small is NG.
For reasons I can't recall, the system is set up with only a 2 GB swap
partition, and for a long while it had a single 4 GB RAM memory stick.
This was OK.
Then I added a second 4 GB memory stick, identical to the first.
With 8 GB RAM and 2 GB swap the system crashed - froze - after a
random few hours.
This was maddening. Not knowing the real cause, I bought a different
motherboard, changed power supply, tried different SATA and ATA
harddrive
connections, changed the SATA cable, removed the extra data drive,
removed the ATA CD drive, used one or the other RAM stick,
disconnected
everything and ran with only a Live F20 Xfce USB stick. I ran
memtest86
for days without error. The only thing that worked was to revert to
only a single memory stick - 4 GB. Either stick was OK.
I put everything back together, using an ATA/SATA converter for the
350 GB primary disk, the SATA 1TB data harddrive, and the ATA CD.
Then I noticed the size of the swap partition was 2 GB and, having
nothing else to try, added an 8 GB swap file.
Eureka! It ran.
I have a matrix of test cases which I won't bore you with.
They can be summarized as follows:
1 - with 4 GB RAM, either 0 or 2 GB swap space is OK.
2 - with 8 GB RAM, 0 swap space is OK.
3 - with 8 GB RAM, 2 GB swap space will reliably freeze the system
4 - with 8 GB RAM, 4 GB swap file is OK.
5 - with 8 GB RAM, 2 GB swap partition + 8 GB swap file is OK,
even if the priority of the smaller one is forced higher.
At no time during these experiments was swap space actually used
according to the gkrellm display; the RAM usage remained well
below what was available.
This is clearly a bug. No rational design would work like this.
Is it a kernel bug? Some other component?
Which one gets the Bugzilla?
