> -----Original Message----- > From: Linux on 390 Port [mailto:[EMAIL PROTECTED]]On Behalf Of > John Summerfield > Sent: Wednesday, April 17, 2002 4:24 PM > To: [EMAIL PROTECTED] > Subject: Re: How to pre-allocate a 4GB File? > > > > Of course, you need some disk-combining facility such as RAID or LVM if > your physical disks are not that big. > > I'm sadly out of touch with mainframe hardware; it seems strange to me > I can get 120 Gbyte disks for my PC and you folk are using 2.3 Gbyte > drives on your mainframes. I know the theoretical limit is larger than > that, and was back when S/360 was announced.
Until very recently, the length of the cylinder count field in a CCW was, iirc, 12 bits; limiting the cylinder range to max of 4096. However, the new ESS (a.k.a SHARK) dasd units now allow "3390" devices to be configured with up to 32760 cylinders, yielding a DASD volume capacity of about 26Gb. z/VM has already been updated to recognize and support these new dasd sizes in both CMS and CP environments. Since the S/3XX architecture got its start when dasd devices where considerably smaller than today's, both the MVS and VM system evolved other ways of handling large files on small devices: MVS has had multi-volume file support for ages, and VM uses the SFS to allow the storage of files up to 17x10**12 bytes in size. Dave Dave
