On Mon, Aug 17, 2009 at 2:12 PM, Manish Rangankar<rangankarmanish@xxxxxxxxx> wrote: > Hi Peter, > > Sorry to bother you again, I was looking at the filesystem code for ufs.h > and I found that there are some metadata which is highly dependent on > whether the OS support 32bit or 64bit. > > Snippet of ufs super block. > > __fs64 fs_size; /* number of blocks in fs */ > __fs64 fs_dsize; /* number of data blocks in > fs */ > __fs64 fs_csaddr; /* blk addr of cyl grp > summary area */ > __fs64 fs_pendingblocks;/* blocks in process of > being freed */ > > Number of data blocks supported on 64-bit(UFS) filesytem will be more then > that of the 32-bit (UFS) filesystem. So if we want 32-bit UFS filesystem(on > 32 bit OS) to support data block as many as 64-bit UFS file sytem then we > have to modify UFS 32 bit filesystem. > > So my question is, whether the 64-bit filesystem is supported on 32-bit OS? > I think it can be supported but with some changes in metadata structure > which will definitely add some performance hit... > > Please confirm if this understanding is correct or not!! > > -Manish R I believe ext4 is currently in the process of getting 64-bit support in. The plan is to make 32-bit function also, but as you say at a slower speed. At least with ext4, 32-bit supports up to 16TB I believe, so it is not a huge issue. I don't know if for instance, a 10 TB filesystem can be created with 64-bit structure. And if it is done, I don't know if a kernel compiled for 32-bit would see a performance impact or not. Greg -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
