Hi. AFAIK, this space is reserved for root logs, in case the filesystem is full, so the kernel won't crash.
>From what I seen, it has to be only enabled on the root partition, the data partitions it can be safely set to 0. I usually leave the default 5% on root, boot and swap (as the space savings there insignificant), and set to 0 on data partition, where it really gives back the 50-60 GB mentioned below. Regards. 2009/10/9 Edward Capriolo <[email protected]> > On a 1tb disk reducing reserved space from 5 to 2 saves almost 30 gb. > Cutting the inodes down saves you some space but not nearly as much. > Say 10 gb. > > The differnce is once you format your disk you can't change the inode > numbers. Tunefs can tune reserved blocks while the disk is mounted. > > I did reserved space with tunefs -m2 > , Noatime then moved on. > > On 10/9/09, stephen mulcahy <[email protected]> wrote: > > paul wrote: > >> Check out the bottom of this page: > >> > >> http://wiki.apache.org/hadoop/DiskSetup > > > > Just re-reading that page, two suggestions that may not be appropriate, > > > > 1. Reducing reserved space to 0. AFAIK, ext3 needs a certain amount of > > free space to function properly - the man page for mke2fs suggests that > > this reserved space is used for defragmentation, as well as being > > emergency space reserved for root. A quick Google doesn't turn up > > anything more definitive, but setting it to 0 is a bad idea afaics. > > > > 2. Reducing the number of inodes. This is a good idea, if you are > > really, really sure that nothing will create small files on that > > partition. Unless you are absolutely certain of this, I would not change > > from the default - I'm not clear on how much of an overall saving you'll > > make and the downside to running to running out of inodes is that you > > start getting "out of space" errors when you try to write to that disk > > (despite df showing you loads of free space), so again, I'm not sure I'd > > recommend this one. > > > > -stephen > > > > -- > > Stephen Mulcahy, DI2, Digital Enterprise Research Institute, > > NUI Galway, IDA Business Park, Lower Dangan, Galway, Ireland > > http://di2.deri.ie http://webstar.deri.ie http://sindice.com > > >
