Chris, A good argument when you are migrating between "like" disk technology and compression of the data is the only saving. However, now that us mainframers have access to cheaper rack & stack storage and SATA disk the economics of migration change, and the savings may be more substantial than before.
With very cheap disk there can be savings realised on ML1 without compression, which would also translate to a MIPS saving. With SATA running at prices similar to tape the economics of disk=ML1 and Tape=ML2 can be turned on its head. IMHO it also makes a whole new ball game for TMM, where savings can be realised with less aggressive interval migration. There are sites out there that measure migrated data in tens of TB, and at least one that counts silos. That's a lot of money saved out of anyone's chequebook, but they probably have rules that are better defined than Mark Z's experience. Avoiding long weekend "thrash" is the first design rule in HSM migration planning. Ron > > Has anyone checked to see whether there's any practical reason (i.e. > $$$) to migrate at all? Disk is pretty cheap these days and HSM is a > notable pig in most shops, ours included. > > I question the value of spending CPU cycles shoveling bits from one cold > place to another - typically in the same array. If it were mine, I'd > leave it spinning on disk until it was so old it had cobwebs on it. Then > if I cared enough about the space, I'd shove it out to a big fat tape > vault and forget about it. YMMV. > > CC > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
