Re: weird instability

Just to wrap up this thread..... doing many things introduced perceived
stability and then everything went to hell in a handbasket, eg, changing
the performance levels of the CPU in the bios, moving /tmp off the SSD to
the hdd

Ran memtest on it, solidly for 14hours, think it got 9 passes in that time,
zero errors.

Limiting the available ram with a kernel command line arguement did work,
took it down to 4GB ram, all ran stable, slow but stable, took it up to 6
then 8 then 12 ... all stable, took it to 16 again with a command line
arguement, crashes, 15, crashes, 14, crashes, and 13 was stable.

So for the benefit of Google, Xubuntu 32bit with 16GB ram, stable up to
13GB of ram, unstable above that, most likely PAE implmentation bug.

Thanks for all your inputs, certainly helped focus.

Harry.

On Wed, Jul 29, 2015 at 2:49 PM, Conor Wynne <[email protected]> wrote:

> Try limiting the memory that the kernel can see by adding a kernel command
> line arg - since you're running on 32-bit albeit with PAE.
>
> On Wed, Jul 29, 2015 at 1:26 PM, Anders Holm <[email protected]> wrote:
>
>> dmesg may also show something that may point yo further, be it RAM or
>> other components....
>>
>> //anders
>>
>>
>> On 29/07/2015 13:20, Rodrigo de Campos wrote:
>>
>> Hi Harry,
>>
>> Sounds like a RAM issue. I understand it's a remote device, but could
>> anyone run memtest for a while? Most ubuntu CDs will come with a preloaded
>> version of memtest. The last time I had those issues, that was basically a
>> flawed RAM stick that I  had to switch to a new working one.
>>
>> I would check it before any further  troubleshooting.
>>
>> Kind Regards,
>> Rodrigo
>>
>> On Wed, Jul 29, 2015 at 9:03 AM, Harry Duncan <[email protected]>
>> wrote:
>>
>>> Guys,
>>>
>>> Got a weird one that one of you might have seen before.
>>>
>>> desktop pc, corei7, 16gb ram, 64gbSSD and 1TB regular disk, running
>>> xubuntu with xfce desktop environment.
>>>
>>> Users tools are Firefox, Thunderbird, Virtualbox and Eclipse
>>>
>>> barely touches a gig of ram consumption when started up
>>>
>>> root@carmen:/home/carmen# uname -a
>>> Linux carmen 3.13.0-58-generic #97-Ubuntu SMP Wed Jul 8 02:56:50 UTC
>>> 2015 i686 i686 i686 GNU/Linux
>>>
>>> Specifically running 32bit for a particular development task that
>>> requires it, and pae to use more ram if needed.
>>>
>>> The disk layout is:
>>>
>>> root@carmen:/home/carmen# fdisk -l
>>>
>>> Disk /dev/sda: 64.0 GB, 64023257088 bytes
>>> 255 heads, 63 sectors/track, 7783 cylinders, total 125045424 sectors
>>> Units = sectors of 1 * 512 = 512 bytes
>>> Sector size (logical/physical): 512 bytes / 512 bytes
>>> I/O size (minimum/optimal): 512 bytes / 512 bytes
>>> Disk identifier: 0x000c7f0f
>>>
>>>    Device Boot      Start         End      Blocks   Id  System
>>> /dev/sda1   *        2048     2099199     1048576   83  Linux
>>> /dev/sda2         2099200    35653631    16777216   82  Linux swap /
>>> Solaris
>>> /dev/sda3        35653632   125045423    44695896   83  Linux
>>>
>>> Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
>>> 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
>>> Units = sectors of 1 * 512 = 512 bytes
>>> Sector size (logical/physical): 512 bytes / 4096 bytes
>>> I/O size (minimum/optimal): 4096 bytes / 4096 bytes
>>> Disk identifier: 0x00004e50
>>>
>>>    Device Boot      Start         End      Blocks   Id  System
>>> /dev/sdb1            2048    62916607    31457280   83  Linux
>>> /dev/sdb2        62916608  1953525167   945304280   83  Linux
>>>
>>>
>>>
>>> root@carmen:/home/carmen# mount
>>> /dev/sda3 on / type ext4 (rw,errors=remount-ro)
>>> proc on /proc type proc (rw,noexec,nosuid,nodev)
>>> sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
>>> none on /sys/fs/cgroup type tmpfs (rw)
>>> none on /sys/fs/fuse/connections type fusectl (rw)
>>> none on /sys/kernel/debug type debugfs (rw)
>>> none on /sys/kernel/security type securityfs (rw)
>>> udev on /dev type devtmpfs (rw,mode=0755)
>>> devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
>>> tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
>>> none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
>>> none on /run/shm type tmpfs (rw,nosuid,nodev)
>>> none on /run/user type tmpfs
>>> (rw,noexec,nosuid,nodev,size=104857600,mode=0755)
>>> none on /sys/fs/pstore type pstore (rw)
>>> /dev/sda1 on /boot type ext2 (rw)
>>> /dev/sdb1 on /var type ext4 (rw)
>>> /dev/sdb2 on /home type ext4 (rw)
>>> binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc
>>> (rw,noexec,nosuid,nodev)
>>> systemd on /sys/fs/cgroup/systemd type cgroup
>>> (rw,noexec,nosuid,nodev,none,name=systemd)
>>> gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse
>>> (rw,nosuid,nodev,user=carmen)
>>> root@carmen:/home/carmen#
>>>
>>>
>>> in summary /boot / and swap on the SSD
>>> /var and /home on the physical disk
>>>
>>>
>>> Problem... on boot up it segfaults on starting every application, each
>>> time getting a little further into the startup sequence, then eventually
>>> the application loads and it runs stable for the remainder of the session.
>>>
>>>
>>> Today I sym linked /tmp to /var/ttmp in case it was a timing issue
>>> between some files being written to the ssd /tmp faster than others could
>>> be written to the regular drive in /var/tmp
>>>
>>> Doesn't seem to have made any improvement.
>>>
>>> The machine is remote to me, was fine when I was there, but being a pain
>>> since. I am going to try and replicate the setup here with regular Debian.
>>>
>>> Can anyone spot any obvious flaw in the above approach that might result
>>> in the applications segfaulting as they load until they sucessfully load
>>> once?
>>>
>>> Anyone heard of this before?
>>>
>>> TIA,
>>>
>>> Harry.
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>>
>>
>>
>> --
>>
>> Rodrigo de Campos
>>
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