On Friday, 10/27/2006 at 09:48 ZE2, Carsten Otte <[EMAIL PROTECTED]> wrote: > Yea I guess so, but not by intention. The wording was not meant to > imply "simple" or "bad". I just intended to state, that due to caching > the consistent view of the data that Linux has is not permanently > reflected on disk. And that is causes trouble when backing up from > outside that guest.
This is true of all operating systems. It is, in general, a Bad Idea to take a backup from the "outside" of a running operating system that is not actively helping you. In z/OS, the extents of a dataset may span multiple volumes. Only the catalog knows for sure. If z/OS is in the process of moving a dataset when you come by and copy the volumes, you will end up with junk. Or with DDR you start copying a volume, say. You have the time-of-test-to-time-of-use problem in disguise. The volume can change while you're copying. The *dataset* you're copying can change. Cache is just one example of the issues surrounding the general problem of data integrity. Alan Altmark z/VM Development IBM Endicott ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
