3590's are "easier" to deal with if you use HSM at all, 3490's have to be set up as a percentage of the 3490 capacity, (otherwise you get something like 800MB tapes (to HSM). While the VTS could care less, it is a pain to have HSM writing 600 tapes a day.
Several sites (about 1/3) we support are using VTL's as 3490's but most are defined as 3590's. The actual numbers are (out of 117 sites with VTL's) 36 are defined as 3490's although almost all of them use a larger tape "size" (some (most) are 2GB some or 5GB and a couple have no limit), whereas the rest of them (81 sites) are defined as 3590's. Speed-wise, I don't think there is a difference, at least not that I can tell. Different VTL vendors seem to use different compression techniques so the sizes vary as to how much actually fits on a tape dataset after compression before it wants to load the next tape. I don't agree (but no one cares) with the sites that don't specify a limit to the tape size. I think that's just asking for a problem somewhere down the line, but if that's what the client wants, we will run that way. If left to my own preferences, I would choose 3590 every time. I also like those VTL's that don't keep the tape/disk storage inside the device and use NetApp or something similar or like EMC does where the DASD is logically pretty separate. Again, that's just a personal preference thing. Brian ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
