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I just got out of a presentation (sales job) from EMC, that they give us every year or two about how EMCs DASD is superior. Presently we have multiple TBs of IBM internal ultra SCSI drives attached to 6532/6533 IOPs on multiple AS/400s, using the 40MB bus. We also follow IBMs white paper for the number of disk arms per system, etc. ***I have seen several opinions about EMC (good and bad) on this list and I am looking for businesses that have switched either way(IBM or EMC) due to support or performance issues (email privately if desired). Often it is easier for some managers to understand a list of dissatisfied customers than explain all of the technical details. The presentation was fun as usually since EMC brought in there "expert" from headquarters, and had three locals to support him. Of course I had to correct the expert several times on ASP storage technicques and main storage processes on the AS/400. They stated that when a page of data (4MB page) is written to any vendors DASD on an AS/400 that it reserves that track of DASD for only that file, so when future data is added to disk for that file it will be contiguous on disk. This is why there "Track Cache" has a 60 to 85% hit ratio. I tried unsuccessfully to explain scattered storage to them. Also they stated expert cache for mainstorage is usually not effective, *CALC ( however here we see up to a 70 % improvement on some batch jobs) *** What have others on the list seen with expert cache? Although EMC DASD attaches to a 6501 which has a 20MB/sec transfer rate and IBMs DASD attaches to a 6533 which has a 40MB/sec transfer rate there DASD is faster? go figure. Also I tried to explain even with if data was contiguous (of course it is not) most people use a lot of logical files to access data so it would be pointless to store data as such. ( Logical files confused them), etc., etc., etc. We invited them t! o do head to head test with our current DASD config. Run batch jobs on our test system using our current IBM DASD and then switch to EMC DASD and run the exact same job mix. Has anyone on this list performed a true head to head test such as this? Thanks for your responses Bob Marion AS/400 Technical Support Plano TX EMail: bob.marion@ps.net +--- | This is the Midrange System Mailing List! | To submit a new message, send your mail to MIDRANGE-L@midrange.com. | To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com. | To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com. | Questions should be directed to the list owner/operator: david@midrange.com +---
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