zRAM broken on Raring?

Sat Sep 28 16:10:26 UTC 2013

Hi, Nio.

That is what puzzled me about Phill's statement that before Saucy, zram 
"was there just not used."

Your confirmation that it is not used in your up-to-date Raring install 
sent me looking for a package that depends on zram-config.  I did a 
Dependencies search in Synaptic and found out that my installed 
ltsp-client package Recommends zram-config.

The nicest solution scenarios would be that zram is fixed in time for 
the Saucy release (there is hope?) and that it is almost simultaneously 
backported to Raring (there is hope?).

But in the meantime I suppose I'll need to talk to the LTSP folks about 
what might be done if neither of the above happens quickly.

--John

On 9/28/2013 4:04 AM, Nio Wiklund wrote:
> Hi John,
>
> I checked in an up to date (update + dist-upgrade) Lubuntu Raring i386
> standard desktop installation. I find no zRAM block devices, no
> zram-config, and nothing else, that indicates that zram should be
> activated. The kernel is 3.8.0.31 #46 according to uname.
>
> guru at pae4pm:~$ uname -a
> Linux pae4pm 3.8.0-31-generic #46-Ubuntu SMP Tue Sep 10 19:56:49 UTC
> 2013 i686 i686 i686 GNU/Linux
>
> I think your zRAM 'came along as a dependency for something'. Maybe you
> have installed some ppa or other special repository to get new kernels
> or other new packages. What version is the kernel in your system?
>
> Best regards
> Nio
>
> On 2013-09-28 01:06, John Hupp wrote:
>> The news/announcements concerning Saucy tend to say something "new in
>> Saucy ... zRAM."
>>
>> But zram-config is installed in my Raring i386 standard desktop
>> installation, and I didn't install it unless it came along as a
>> dependency for something.
>>
>> On 9/27/2013 6:29 PM, Nio Wiklund wrote:
>>> Sorry, I overlooked that John is running Raring. I didn't think zRAM was
>>> used in Raring, but of course, John can install and run it. I'm glad you
>>> corrected that mistake by me.
>>>
>>> Best regards
>>> Nio
>>>
>>> On 2013-09-28 00:08, Phill Whiteside wrote:
>>>> hi Nio,
>>>>
>>>> he is running Raring. The bug we see in Saucy on 1227202 is totally
>>>> un-related to the sudo parted -l issue.
>>>>
>>>> Getting the race issue sorted out on un-mounting the zram areas is what
>>>> the bug fix is. With all the tests I've done, the
>>>>
>>>>    Error: /dev/zram0: unrecognised disk label
>>>>
>>>> Error: /dev/zram1: unrecognised disk label
>>>>
>>>> Has remained until I used the 3.12rc kernel. We will go battle that
>>>> issue on Monday to see if we can find the fix. Also do
>>>> read https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1215379 as we
>>>> may be barking up the wrong tree with zram, and should be using zswap.
>>>>
>>>> Joe cannot tell us which is better to use, just that zswap was in the
>>>> 3.11.2 upstream kernel which has been imported into the latest
>>>> 3.11.0-9.16 kernel.
>>>>
>>>> It was Unit193 who pointed that issue out, and whilst getting the race
>>>> crash sorted out, it appears that zswap is the updated system.
>>>>
>>>> Regards,
>>>>
>>>> Phill.
>>>>
>>>>
>>>> On 27 September 2013 22:54, Nio Wiklund <nio.wiklund at gmail.com
>>>> <mailto:nio.wiklund at gmail.com>> wrote:
>>>>
>>>>       On 2013-09-27 23:28, John Hupp wrote:
>>>>       > On Raring, output from 'sudo parted -l' includes:
>>>>       >
>>>>       >     Error: /dev/zram0: unrecognised disk label
>>>>       >
>>>>       > And syslog shows a slew of errors:
>>>>       >
>>>>       >     Lubuntu kernel: Buffer I/O error on device zram0, logical
>>>>       block 128247
>>>>       >
>>>>       > Syslog also indicates that half of memory was given to zram to
>>>>       form its
>>>>       > block device.
>>>>       >
>>>>       > Does this mean that half of memory is dedicated to something that
>>>>       isn't
>>>>       > working?  And perhaps that machines will hang when swap is
>>>> needed?
>>>>       >
>>>>       > I arrive at this line of questioning because I was testing an
>>>> LTSP
>>>>       > client using a Lubuntu LTSP server configured with 1 GB, and when
>>>>       I drop
>>>>       > the client memory configuration to 256 MB, the *server* has
>>>> hung on
>>>>       > several occasions when I was starting or stopping Firefox on the
>>>>       client
>>>>       > (though in one case this coincided with the startup of a
>>>> SpiderOak
>>>>       > backup operation).   I didn't think of the Magic SysRq keys at
>>>> the
>>>>       time,
>>>>       > and nothing else was responding, so I did hard shutdowns.
>>>>       >
>>>>       > I saw a post from Phill Whiteside recently concerning a rush of
>>>>       activity
>>>>       > re a zram bug, but it seemed to be directed at Saucy.
>>>>       >
>>>>       > Are there solutions/workarounds?
>>>>       >
>>>>       You find a lot of details reading the comments about this bug.
>>>>
>>>>       https://bugs.launchpad.net/bugs/1227202
>>>>
>>>>       There is a kernel in the pipeline, that we think will solve most
>>>> if not
>>>>       all of the problems. Until we get the kernel that can cooperate
>>>> with
>>>>       zRAM, you can switch it off either manually or with crontab like
>>>> this:
>>>>
>>>>       guru at Lubuntu-Saucy-b2:~$ sudo crontab -l |tail -n3
>>>>       # m h  dom mon dow   command
>>>>       @reboot              /sbin/swapoff /dev/zram*
>>>>       @reboot              /sbin/rmmod zram
>>>>
>>>>       Best regards
>>>>       Nio
>>>>
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>>>>
>>>>
>>>>
>>>> -- 
>>>> https://wiki.ubuntu.com/phillw