[Fedora-livecd-list] persistence testing howto
Douglas McClendon
dmc.fedora at filteredperception.org
Fri Jan 4 03:06:14 UTC 2008
Mike Dickson wrote:
> I just finished trying to download JBoss Developer Studio and installing
> it on the thumb drive. It filled up again. I then dropped the .jar on
> the stick hoping that I could install from that and it filled up again.
> Checkmate.
What size snapshot file are you using? I think my example used 128M,
which was of the mindset of a 700MB livecd and a 128M persistence file
on a 1G liveusb.
You might have better luck with a 1G persistence file on a 2G usbstick.
In general what you really want to do is install the main stuff as part
of the spin, and only use the persistence feature for the end-users so
they can install some smaller one-off library (or such) for their
particular needs.
Likewise, persistence can be used to edit /etc/fstab permanently to
mount a seperate /home partition from a different filesystem image file,
which won't suffer some of these issues (but obviously isn't useful for
yum installing anything).
Gotta get back to watching the bowl... At some point I hope to write up
a web page better describing the mechanisms here, to help people
understand the limitations of this method, and how best to work around
them. This is definitely not a magic bullet solution.
more later...
-dmc
>
> MikeD
>
> On Thu, 2008-01-03 at 15:30 -0800, Mike Dickson wrote:
>> Ran that and yes the snapshot area filled up BEFORE the errors. Let
>> me know what I can do....
>>
>> MikeD
>>
>> On Thu, 2008-01-03 at 16:31 -0600, Douglas McClendon wrote:
>>> Mike Dickson wrote:
>>> > Guys,
>>> >
>>> > I got a LiveCD + Persistence usb drive running from your scripts, but
>>> > got I/O errors if I tried to do a yum update.
>>> >
>>> > Before that I was able to vi test.txt and put some text in and it
>>> > survived a reboot.
>>> >
>>> > What can I do to address the i/o errors?
>>>
>>> My first question/explanation would be that you filled up the snapshot
>>> device. This is quite possible, as a yum install involves creating
>>> several copies of the actual files you end up installing.
>>>
>>> The way to see if this is what is happening would be to have another
>>> terminal open, and periodically watch the output of "dmsetup status".
>>> As new blocks are written to the rootfs snapshot device, you will see
>>> the snapshot filling up.
>>>
>>> If you get these IO errors even before the snapshot fills up, please try
>>> to post some more detailed output.
>>>
>>> In general, as discussed there are pros and cons with this method, and a
>>> unionfs method. I do think there are ways to work around the cons of
>>> this method in such a way that it is useful. For instance, I'll play
>>> around and see if I can prescribe a process of using yum that will get
>>> it to create all of its intermediate files in a native tmpfs (/dev/shm
>>> or the like) instead of the rootfs, so that they don't eat into the
>>> snapshot space. Likewise, now that I have my first actual tester, maybe
>>> I'll figure out some other creative ways to improve the method (I have
>>> some ideas I need to experiment with...).
>>>
>>> Thanks,
>>>
>>> -dmc
>>>
>>>
>>>
>>> >
>>> > MikeD
>>> >
>>> > "Messsage from syslogd at localhost <mailto:syslogd at localhost> at
>>> > kernel: journal commit i/o error"
>>> >
>>> >
>>> > On Wed, 2008-01-02 at 04:07 -0800, Mike Dickson wrote:
>>> >> I have some time now. I am attempting this tonight and tomorrow. I
>>> >> will let you know.
>>> >>
>>> >> MikeD
>>> >>
>>> >
>>> >
>>> > ------------------------------------------------------------------------
>>> >
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>>>
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