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>> 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> > > > > > -- > Regards, > Danny > > > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
