[gentoo-user] jbd2 keeps spinning my disk up

[gentoo-user] jbd2 keeps spinning my disk up

[Peter Humphrey]

Hello list,

My little Atom box's hard disk spins up every minute or so, and watching 
iotop I see it's jbd2 that does it.

This is a kernel component, and the menuconfig help text says it's set 
automatically by having the block layer included (and who hasn't?) together 
with ext4.

Google shows that others have similar problems.

Before I re-create all the partitions as reiserfs - and remove ext4 from the 
kernel - does anyone have a lighter solution?

-- 
Rgds
Peter		Linux Counter 5290, 1994-04-23

Re: [gentoo-user] jbd2 keeps spinning my disk up

[Michael Mol]

On Sun, Jul 31, 2011 at 11:50 AM, Peter Humphrey
<peter@humphrey.ukfsn.org> wrote:
> Hello list,
>
> My little Atom box's hard disk spins up every minute or so, and watching
> iotop I see it's jbd2 that does it.
>
> This is a kernel component, and the menuconfig help text says it's set
> automatically by having the block layer included (and who hasn't?) together
> with ext4.
>
> Google shows that others have similar problems.
>
> Before I re-create all the partitions as reiserfs - and remove ext4 from the
> kernel - does anyone have a lighter solution?

If it's a polling commit-journal-to-disk behavior, there's certain to
be a configurable parameter somewhere to control the poll rate.

However, if it's doing that, then it probably has something it needs
to write to disk. That might be metadata updates. Have you tried
adding things to your mount parameters like 'noatime' or 'relatime'?
What about "data=writeback"?

-- 
:wq

Re: [gentoo-user] jbd2 keeps spinning my disk up

[Peter Humphrey]

On Sunday 31 July 2011 17:05:39 Michael Mol wrote:

> However, if it's doing that, then it probably has something it needs to
> write to disk. That might be metadata updates.

What, at least once a minute? While the system's idling, waiting for 
something to do? Doesn't sound likely to me.

> Have you tried adding things to your mount parameters like 'noatime' or
> 'relatime'?

I've been specifying 'noatime' on all partitions for several years now; it's 
automatic behaviour on my part.

> What about "data=writeback"?

I don't like the sound of the warning in the man page.

Thanks for the ideas. So far I'm inclining to the reformatting I mentioned.

-- 
Rgds
Peter		Linux Counter 5290, 1994-04-23

Re: [gentoo-user] jbd2 keeps spinning my disk up

[Alan McKinnon]

On Sun 31 July 2011 18:39:21 Peter Humphrey did opine thusly:
> On Sunday 31 July 2011 17:05:39 Michael Mol wrote:
> > However, if it's doing that, then it probably has something it
> > needs to write to disk. That might be metadata updates.
> 
> What, at least once a minute? While the system's idling, waiting for
> something to do? Doesn't sound likely to me.

Sounds like the kind of thing cron would do - log something once a 
minute

-- 
alan dot mckinnon at gmail dot com

Re: [gentoo-user] jbd2 keeps spinning my disk up

[Michael Mol]

On Sun, Jul 31, 2011 at 1:39 PM, Peter Humphrey
<peter@humphrey.ukfsn.org> wrote:
> On Sunday 31 July 2011 17:05:39 Michael Mol wrote:
>
>> However, if it's doing that, then it probably has something it needs to
>> write to disk. That might be metadata updates.
>
> What, at least once a minute? While the system's idling, waiting for
> something to do? Doesn't sound likely to me.
>
>> Have you tried adding things to your mount parameters like 'noatime' or
>> 'relatime'?
>
> I've been specifying 'noatime' on all partitions for several years now; it's
> automatic behaviour on my part.
>
>> What about "data=writeback"?
>
> I don't like the sound of the warning in the man page.
>
> Thanks for the ideas. So far I'm inclining to the reformatting I mentioned.

Here's what I think is happening:

ext3/ext4 is not going to arbitrarily poll writes to disk without
there being something to write. Some program, somewhere on your system
is doing something that involves modifying a file. Any filesystem that
provides guarantees about disk integrity is going to get that data to
a physically persistent state ASAP. That's why we have journaled
filesystems in the first place: to speed that up.

So, with the same application and configuration set, you're going to
see the same behavior on any filesystem which provides such
guarantees.

You're perfectly welcome to reformat if you're so inclined; it really
sounds like you're simply more comfortable (or more interested in)
reiserfs. If you perceive that that solve your problem, great--but I
don't think that would really solve the underlying technical issue.

What you really want to do is find some way to log what's actually
driving the data writes. If it were a particular app, it'd be as
simple as launching the app via strace and analyzing the output. I
don't know how one would do that system-wide, though. Perhaps someone
else might have ideas.

-- 
:wq

Re: [gentoo-user] jbd2 keeps spinning my disk up

[Florian Philipp]

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Am 31.07.2011 17:50, schrieb Peter Humphrey:
> Hello list,
> 
> My little Atom box's hard disk spins up every minute or so, and watching 
> iotop I see it's jbd2 that does it.
> 
> This is a kernel component, and the menuconfig help text says it's set 
> automatically by having the block layer included (and who hasn't?) together 
> with ext4.
> 
> Google shows that others have similar problems.
> 
> Before I re-create all the partitions as reiserfs - and remove ext4 from the 
> kernel - does anyone have a lighter solution?
> 

Does laptop-mode help?
app-laptop/laptop-mode-tools

Regards,
Florian Philipp


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Re: [gentoo-user] jbd2 keeps spinning my disk up

[Peter Humphrey]

On Sunday 31 July 2011 22:40:28 Florian Philipp wrote:

> Does laptop-mode help?
> app-laptop/laptop-mode-tools

I hadn't thought of that - thanks. I'll try it and see.

-- 
Rgds
Peter		Linux Counter 5290, 1994-04-23

[gentoo-user] Re: jbd2 keeps spinning my disk up

[James]

Peter Humphrey <peter <at> humphrey.ukfsn.org> writes:


> My little Atom box's hard disk spins up every minute or so, and watching 
> iotop I see it's jbd2 that does it.

> Google shows that others have similar problems.

> Before I re-create all the partitions as reiserfs - and remove ext4 from the 
> kernel - does anyone have a lighter solution?

Well, lots in good responses, so please do not interpret
mine as saying it's a better solution that what
others are suggestion.

Atom is more of an embedded processor than
a true workstation/server processor, imho.
As such, it it more "bare metal" meaning
countless software developments for AMD and
Intel processors intended for workstations
and servers, are irrelevant, useless, harmful,
redundant, or just plain stupid for embedded
processors. like the atom.

So now you (and I and millions of folks) are
trying to use mega-software (linux distro)
on a bare-metal processor....

NOBODY has fleshed out these issues on an itemized
basis. i.e. the knowledge base is sparse (at best)
since the only one that can really do this is the
silicon vendors and they have a VESTED INTEREST
in not doing so. Furthermore, since Atom and ARM
and many other embedded processors are combined
as "cores" on an SOC (system on a chip) each
revision of such hardware by each vendor can have
different addtional hardware on the SOC that a generic
compiled software distro is clueless about.
 That's why numerous devices
that attempt low power linux, use a proprietary
linux based on montaVista or countlesss other
embedded linux vendors. These purveyors and vendors
of the various embedded linux offerings do not
publish anything about these hardware details
for some issues and do include documentation,
deep in the specifications of the processor.

When you stray from that (the linux distro that
come with the product), you are on your own,
finding piecemeal information about low level
hardware intricacies....ad-nossium.....imho.
If the device came with some OS other than a
linux hack..... YOu are much futher from
paradise then with a default linux distro
as the OS the vendor provided. It does not mean
you will not be successful, just your journey
is perilous, at best, if optimization is
what you seek.


Long story short, for years I have been building
firewalls and embedded linux bridges, sniffers
and other passive ethernet based devices,
using ext2. Works beautifully with little
attention. Not optimized, but avoid a HUGE
time-sink.

I encounter a myriad of issues, when trying
newer file systems for embedded linux systems.
Ext-2 works for years on Compact Flash drives
if you do not log, or limit logs to an NFS link
or such. As one reader suggested, you have to
audit, one application at a time, to find the culprit.
It's actually a never ending process, imho,
as feature creep on a myriad of software packages
will usually lead to performance issues and thus
more aggressive algorithms on data movement.

You may want to try some of the file systems
intended for embedded system (as part of the 
newer linux kernels)  and the tuning
parameters therein, if you are looking for
a robust solution. Also delete what you do
not need from the atom based system, just
as a general policy. Minimal and embedded
are different facets of the same thing.

Intel atom is first and foremost an embedded
processor, not a CISC processor. I.E. just
because it compiles, does not mean it runs
well on limited resources or bare metal.


Happy Hunting,
James