-----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of R.S. Sent: Thursday, July 18, 2013 15:21 To: [email protected] Subject: Re: RMM v/s TS7740 VTS
W dniu 2013-07-18 13:52, Vernooij, CP - SPLXM pisze: > 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. > > Not exactly. RMM does provide information about dataset size (uncompressed) and volume utilization (real). So, assuming single file volume, it is possible to have 35% tape utilized (65% free) and dataset size at 90% or 130% of volume size. That makes sense for physical volume, because I know how much space left on the cart. It doesn't make to much sense on virtual tape, since it's better & easier to taker another virtual volume. BTW: virtual volumes do have defined max size (increased few years ago due to some factors), but having virtual tape "underutilized" is not waste of real resources. (fine print on) IBM VTS solutions do have limit of total virtual volumes. This is one of the reasons why the virt. vol. size was increased. While very little-utilized volumes do not waste real resources they consume the above limit. Note, it's not a problem in STK/Sun/Oracle product, because there is no limitation for VTVs. -- Correct. However there is an advantage in underutilized logical volumes: a CA-DISK restore (~HSM recall) from a logical volume that is not in the VTS cache, can only begin when the full logical volume has been recalled to the VTS cache. Therefor I deliberately use small logical volumes (1GB i.s.o 4GB standard)for (~HSM) Level2 tapes in order to minimize the delay of the real restoring of the dataset to disk. Kees. ******************************************************** For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. Koninklijke Luchtvaart Maatschappij NV (KLM), its subsidiaries and/or its employees shall not be liable for the incorrect or incomplete transmission of this e-mail or any attachments, nor responsible for any delay in receipt. Koninklijke Luchtvaart Maatschappij N.V. (also known as KLM Royal Dutch Airlines) is registered in Amstelveen, The Netherlands, with registered number 33014286 ******************************************************** ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
