About RMM: No. Since the physical 3480 tape control unit, the result of the IDRC compression, done by the control unit, can be queried by the software. CA-1 does this since a long time and I understood RMM does too. This enables the tapemanagement software to record both the 100GB and the 25GB values.
Kees. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of R.S. Sent: Thursday, July 18, 2013 13:18 To: [email protected] Subject: Re: RMM v/s TS7740 VTS (Displaimer: Maybe I missed the point or misunderstood something) Do simple test, you need only your imagination: You have 100GB big dataset on your (mainframe) DASD. You keep there some AVI movies. The SYS1.MOVIE dataset occupy ~100GB on DASD, ~100GB will be transmitted through the FICONs channels, ~100GB on VTS disk cache and finally ~100GB on backend tape. Now you have SYS1.NORMAL dataset with typical, compressible data, let's assume 4:1 compression So, ~100GB on DASD ~100GB sent by channel cards from the CPC ~100GB received by channel adapters by the VTS (compression in-flight) ~25GB stored on VTS disk cache ~ 25GB of data can be destaged on backend (real) tape. Now what about RMM? RMM should show you dataset size ~100GB in both cases. That's the size of your dataset, not the space occupied by the dataset on any medium. Just number of blocks * blocksize (assuming equal blocks). What about VOL size, free space on the volume? That's ...irrelevant! Your volumes are virtual, you don't care about free space left on the tape volume, because the space does not exist and does not waste any resource. What about backend tape? Well, that should be VTS responsibility. ;-) -- Radoslaw Skorupka Lodz, Poland W dniu 2013-07-18 01:01, Munish Sharma pisze: > Hello > I am researching on TS7740 VTS, as it reaching the VTS Throughput limit and > done some initial analysis with VEHSTATS. > To narrow down to alias level reporting, for who is using how much at what > point of time..I am using RMM report. I am struck at a point, where I do not > understand.. if RMM says in panels a DSN is 100GB, but in RMM report DSIZE is > zero (most cases) .. and comparatively minimum data(lets say 6-7 GB), under > Variable(Actual amount of Data on Tape) .. in RMM report. > > So, If RMM Panels says TAPE DSN was 100 GB.. but 6-7 GB on real tape.. I > understand compression does that.. > > > NOW the question is ... DOES VTS do any I/O initially while creating 100GB > or is it compressing while write to VTS and not creating 100GB( just fake it > ).. So does that do I/O for 100 GB while writing to VTS or 25gb as if > compressed? > > Another scenario.. If a Compressed Data on Backend tape was 3982 MB and 25244 > MB in VTS.. after coming to VTS .. Does this DSN uses 25 GB space in VTS or > virtualization keep it at 3982 MB even in VTS (just fake it)... So, when Host > going to read it back, does it read 25GB, or 3982 MB? > > > Please let me know, how to look at it.. > > Regards > Munish Sharma > > People are Awesome.... > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > . > -- Treść tej wiadomości może zawierać informacje prawnie chronione Banku przeznaczone wyłącznie do użytku służbowego adresata. Odbiorcą może być jedynie jej adresat z wyłączeniem dostępu osób trzecich. Jeżeli nie jesteś adresatem niniejszej wiadomości lub pracownikiem upoważnionym do jej przekazania adresatowi, informujemy, że jej rozpowszechnianie, kopiowanie, rozprowadzanie lub inne działanie o podobnym charakterze jest prawnie zabronione i może być karalne. 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