In PC terms, there is "low level formatting" and "high level formatting". On Linux/390, 'dasdfmt' handles low level and 'mke2fs' does high level. The former is mostly just pre-blocking all tracks on the disk at 4K. The latter is actually creating a filesystem.
In CMS, the FORMAT command does both: blocking and filesystem. In MVS, the distinction is really lost. All other contemporary operating systems with any presence in the public mind split the blocking of disk storage from the creation of the filesystem (if any). To your question: There is some loss of raw capacity in inter-record gaps when you write the blocks. There is additional (small) loss of capacity in the logic of the filesystem. There is ALSO some reserved space on most POSIX filesystems (usu 5-10%). I hope this helps. -- R; On Tue, Jun 3, 2008 at 9:56 AM, Martin, Terry R. (CMS/CTR) (CTR) < [EMAIL PROTECTED]> wrote: > Hi > > > > So is it the FORMATING in VM (CPFMTXA) or is it what Linux is doing in > their formatting that is causing the difference in the available space on > the MOD-9? > > > > > > > > *Thanks.. Terry* > > *Terry Martin* > *Lockheed Martin - CITIC* > *z/OS Performance and Tuning * > *(410) 786-0386 - Office* > *(443) 632-4191 - Cell* > [EMAIL PROTECTED] > > * * > ------------------------------ > > *From:* The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] *On > Behalf Of *Ivica Brodaric > *Sent:* Monday, June 02, 2008 11:39 PM > *To:* [email protected] > *Subject:* Re: 3390-MOD9 > > > > When you format the disk in VM, you get 4K blocks. Therefore: > > 4K * 180blk/cyl * 10017 cyl = 6.9GB > -- -- R; <><
