Performance benefits of ECS are very significant. However, be mindful that ENQ is mostly but not entirely eliminated.
Terry Traylor charlesSCHWAB TIS Mainframe Storage Management Remedy Queue: tis-mfs-storage (602) 977-5154 WARNING: All email sent to or from this address will be received by the Charles Schwab corporate e-mail system and is subject to archival and review by someone other than the recipient. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of TISLER Zaromil Sent: Monday, March 20, 2006 11:33 PM To: IBM-MAIN@BAMA.UA.EDU Subject: Re: Enhanced Catalog Sharing > What is the gain or the advantage of using ECS. >From an old redbook (Enhanced Catalog Sharing and Management, SG24-5594-00, July 1999): --- When CAS opens an eligible catalog and the system is in catalog sharing mode, as described in "Activating ECS" on page 18, the integrity VVR is copied into the Coupling Facility structure. Once this occurs, the systems that share the catalog do not have to read the VVR to detect change, as they will receive notification from the Coupling Facility. Also, the requirement to ENQ on the resource is removed because the Coupling Facility architecture incorporates the necessary locking. --- and --- This is an elegant solution to the performance issues. The elapsed time is reduced because GRS is no longer used, and the number of I/Os is reduced because the VVR does not have to be read. Also, the new function fits smoothly alongside the existing reliable and robust code, which will still be used for non-ECS catalogs. Non-ECS catalogs are now described as being in VVDS mode, which indicates that the VVR is being read from the VVDS. In the rare circumstance of a connectivity or Coupling Facility structure failure, the ECS catalogs will revert to VVDS mode, allowing the integrity of the catalogs to be maintained across such a failure. --- Zaromil ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
