AdaTheDev | 18 Mar 09:27 2011
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Forcing enabling/disabling of journal file pre-allocation

Is it possible to control whether or not mongodb preallocates journal
files?

I'm just running some tests to get some performance benchmarks of
journaling, and the first time I started mongodb with --journal it
didn't preallocate the journal files, subsequent times it has
preallocated them.

AdaTheDev | 18 Mar 09:39 2011
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Re: Forcing enabling/disabling of journal file pre-allocation

To be more specific, I have 2 drives:
Drive 1 = SAS drive
Drive 2 = SATA drive

mongo data is on drive 2. When I run with the journal directory on
drive 2, the journal files are never preallocated. When I set up a
junction to map the journal directory on to drive 1 instead, it always
preallocates the journal files there. So when performance testing the
difference of having the journals on the same or separate disks, I
can't seem to get a common baseline to start from.

On Mar 18, 8:27 am, AdaTheDev <adathe...@...> wrote:
> Is it possible to control whether or not mongodb preallocates journal
> files?
>
> I'm just running some tests to get some performance benchmarks of
> journaling, and the first time I started mongodb with --journal it
> didn't preallocate the journal files, subsequent times it has
> preallocated them.

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Scott Hernandez | 18 Mar 13:15 2011
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Re: Re: Forcing enabling/disabling of journal file pre-allocation

Yes, it does a little testing to see if there is an advantage to
preallocating the files or not.
http://www.mongodb.org/display/DOCS/Journaling

You can manually pre-allocate the files so the tests have a common
starting point.
http://www.mongodb.org/display/DOCS/Journaling+Administration+Notes

On Fri, Mar 18, 2011 at 8:39 AM, AdaTheDev <adathedev@...> wrote:
> To be more specific, I have 2 drives:
> Drive 1 = SAS drive
> Drive 2 = SATA drive
>
> mongo data is on drive 2. When I run with the journal directory on
> drive 2, the journal files are never preallocated. When I set up a
> junction to map the journal directory on to drive 1 instead, it always
> preallocates the journal files there. So when performance testing the
> difference of having the journals on the same or separate disks, I
> can't seem to get a common baseline to start from.
>
>
> On Mar 18, 8:27 am, AdaTheDev <adathe...@...> wrote:
>> Is it possible to control whether or not mongodb preallocates journal
>> files?
>>
>> I'm just running some tests to get some performance benchmarks of
>> journaling, and the first time I started mongodb with --journal it
>> didn't preallocate the journal files, subsequent times it has
>> preallocated them.
>
(Continue reading)

AdaTheDev | 18 Mar 13:43 2011
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Re: Forcing enabling/disabling of journal file pre-allocation

Thanks Scott - I ended up manually pre-allocating the files for the
time when it didn't automatically.
The only scenario I couldn't test was NOT having preallocation done on
the faster SAS drive - as it doesn't look like you can stop it
automatically preallocating (and after it's done it, you cant drop the
files while mongod is running)

On Mar 18, 12:15 pm, Scott Hernandez <scotthernan...@...> wrote:
> Yes, it does a little testing to see if there is an advantage to
> preallocating the files or not.http://www.mongodb.org/display/DOCS/Journaling
>
> You can manually pre-allocate the files so the tests have a common
> starting point.http://www.mongodb.org/display/DOCS/Journaling+Administration+Notes
>
>
>
>
>
>
>
> On Fri, Mar 18, 2011 at 8:39 AM, AdaTheDev <adathe...@...> wrote:
> > To be more specific, I have 2 drives:
> > Drive 1 = SAS drive
> > Drive 2 = SATA drive
>
> > mongo data is on drive 2. When I run with the journal directory on
> > drive 2, the journal files are never preallocated. When I set up a
> > junction to map the journal directory on to drive 1 instead, it always
> > preallocates the journal files there. So when performance testing the
> > difference of having the journals on the same or separate disks, I
(Continue reading)

Scott Hernandez | 18 Mar 13:47 2011
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Re: Re: Forcing enabling/disabling of journal file pre-allocation

No, you should not remove the journal files while mongodb is running.

Are you running on windows?

On Fri, Mar 18, 2011 at 12:43 PM, AdaTheDev <adathedev@...> wrote:
> Thanks Scott - I ended up manually pre-allocating the files for the
> time when it didn't automatically.
> The only scenario I couldn't test was NOT having preallocation done on
> the faster SAS drive - as it doesn't look like you can stop it
> automatically preallocating (and after it's done it, you cant drop the
> files while mongod is running)
>
> On Mar 18, 12:15 pm, Scott Hernandez <scotthernan...@...> wrote:
>> Yes, it does a little testing to see if there is an advantage to
>> preallocating the files or not.http://www.mongodb.org/display/DOCS/Journaling
>>
>> You can manually pre-allocate the files so the tests have a common
>> starting point.http://www.mongodb.org/display/DOCS/Journaling+Administration+Notes
>>
>>
>>
>>
>>
>>
>>
>> On Fri, Mar 18, 2011 at 8:39 AM, AdaTheDev <adathe...@...> wrote:
>> > To be more specific, I have 2 drives:
>> > Drive 1 = SAS drive
>> > Drive 2 = SATA drive
>>
(Continue reading)

AdaTheDev | 18 Mar 14:00 2011
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Re: Forcing enabling/disabling of journal file pre-allocation

Yes, Win 7 64Bit. I have no production requirement to prevent
preallocation, it's purely for some testing on my local machine. Very
much a "nice-to-have" to complete a set of performance tests I've been
running

On Mar 18, 12:47 pm, Scott Hernandez <scotthernan...@...> wrote:
> No, you should not remove the journal files while mongodb is running.
>
> Are you running on windows?
>
>
>
>
>
>
>
> On Fri, Mar 18, 2011 at 12:43 PM, AdaTheDev <adathe...@...> wrote:
> > Thanks Scott - I ended up manually pre-allocating the files for the
> > time when it didn't automatically.
> > The only scenario I couldn't test was NOT having preallocation done on
> > the faster SAS drive - as it doesn't look like you can stop it
> > automatically preallocating (and after it's done it, you cant drop the
> > files while mongod is running)
>
> > On Mar 18, 12:15 pm, Scott Hernandez <scotthernan...@...> wrote:
> >> Yes, it does a little testing to see if there is an advantage to
> >> preallocating the files or not.http://www.mongodb.org/display/DOCS/Journaling
>
> >> You can manually pre-allocate the files so the tests have a common
> >> starting point.http://www.mongodb.org/display/DOCS/Journaling+Administration+Notes
(Continue reading)


Gmane