On 6/24/16 5:34 AM, Danny Shavit wrote:
>> How do you determine allocated_size, with du?
> yes via du
>> How different? Can you show an example?
> meta data file size= 5.6 GB (*6,089,374,208*)
>
> *df:*
> Filesystem 1K-blocks Used Available Use% Mounted on
> /dev/dm-39 2725683200 955900860 1769782340 36% /export/v1
> = 978,842,480,640 bytes
>
> *du:* du -s /export/v1/
>
> 952825644 /export/v1/ = 975,693,459,456 bytes
> 978,842,480,640 -975,693,459,456 =
>
> Metadata size according to calculation=*3,149,021,184* bytes
Oh, right. I should have thought of this; "du" counts some metadata as
well, i.e. a directory full of zero-length files still consumes space
which is reported by du.
so your 975,693,459,456 bytes is file data as well as some metadata.
-Eric
>
> Thanks,
> Danny
>
> On Thu, Jun 23, 2016 at 9:12 PM, Eric Sandeen <sandeen@xxxxxxxxxxx
> <mailto:sandeen@xxxxxxxxxxx>> wrote:
>
> On 6/23/16 10:04 AM, Danny Shavit wrote:
> > I see. We will try this direction.
> > BTW: I thought that good estimate would be "volume_size -
> > allocated_size - free_space". But it produced quite a difference
> > compared to metadata dump size.
> > Is there a specific reason?
>
> How do you determine allocated_size, with du?
>
> How different? Can you show an example?
>
> -Eric
>
> > Thanks,
> > Danny
> >
> > On Thu, Jun 23, 2016 at 1:51 AM, Dave Chinner <david@xxxxxxxxxxxxx
> <mailto:david@xxxxxxxxxxxxx> <mailto:david@xxxxxxxxxxxxx
> <mailto:david@xxxxxxxxxxxxx>>> wrote:
> >
> > On Wed, Jun 22, 2016 at 06:58:16PM +0300, Danny Shavit wrote:
> > > Hi,
> > >
> > > We are looking for a method to estimate the size of metadata
> overhead for a
> > > given file system.
> > > We would like to use this value as indicator for the amount of
> cache memory
> > > a system for faster operation.
> > > Are there any counters that are maintained in the on-disk data
> > > structures like free space for examples?
> >
> > No.
> >
> > Right now, you'll need to take a metadump of the filesystem to
> > measure it. The size of the dump file will be a close indication of
> > the amount of metadata in the filesystem as it only contains
> > the filesystem metadata.
> >
> > In future, querying the rmap will enable us to calculate it on the
> > fly, (i.e. not requiring the filesystem to be snapshotted/taken off
> > line to do a metadump).
> >
> > Cheers,
> >
> > Dave.
> > --
> > Dave Chinner
> > david@xxxxxxxxxxxxx <mailto:david@xxxxxxxxxxxxx>
> <mailto:david@xxxxxxxxxxxxx <mailto:david@xxxxxxxxxxxxx>>
> >
> >
> >
> >
> > --
> > Regards,
> > Danny
> >
> >
> > _______________________________________________
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> > xfs@xxxxxxxxxxx <mailto:xfs@xxxxxxxxxxx>
> > http://oss.sgi.com/mailman/listinfo/xfs
> >
>
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>
>
>
> --
> Regards,
> Danny
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