lezo@syma.sussex.ac.uk (Lez Oxley) (02/15/91)
Data Compression Devices are now available for 8mm, 4mm and .5 inch SCSI Tape Drives to enhance data transfer rates and to increase tape capacity up to 4 times. Typically, it is claimed that an Exabyte cartridge could now hold up to 6.6 gigabytes of data. Digidata market a model 4000 (tm) data compressor and Peripheral Vision Corporation market a 4Sight (tm) Data Compression module. There are other products on the market as well. Has anyone out there in netland got any experience of these kinds of devices? How do their claims bear up in practice? How reliable are these devices? Has an industry 'compression' standard emerged yet? If so what devices should one go for? Or is it best to wait awhile until this (new?) technology is proven? We have a Sequent S27 and Sequent Exabyte and are interested increasing our backup capability. Are Sequent doing any work in this area that they can tell us about? What kind of device will they be supporting in future to cope with the backing up of large databases? -- Lez Oxley, Administration, University of Sussex, Brighton, BN1 9RH, UK Tel: +44 273 606755 x3808 Fax: +44 273 678335 JANET: lezo@uk.ac.sussex.syma ARPA: lezo%syma.sussex.ac.uk@nsfnet-relay.ac.uk BITNET: lezo@syma.sussex.ac.uk UUCP: lezo@syma.uucp
ben@epmooch.UUCP (Rev. Ben A. Mesander) (02/19/91)
>In article <4501@syma.sussex.ac.uk> lezo@syma.sussex.ac.uk (Lez Oxley) writes: > >Data Compression Devices are now available for 8mm, 4mm and .5 inch SCSI >Tape Drives to enhance data transfer rates and to increase tape capacity >up to 4 times. Typically, it is claimed that an Exabyte cartridge could >now hold up to 6.6 gigabytes of data. > >Digidata market a model 4000 (tm) data compressor and Peripheral Vision >Corporation market a 4Sight (tm) Data Compression module. There are >other products on the market as well. [Bunches 'O Questions] I have one more question to add: How do these products perform when dumping already compressed data to disk? I already keep stuff I don't need very often compressed. Are these boards "smart" enough to keep from expanding the data? -- ben@epmooch.UUCP ben%servalan.UUCP@uokmax.ecn.uoknor.edu {chinet,uokmax}!servalan!epmooch!ben (Ben Mesander) War in gulf: newpath 288 396 216 0 360 arc 288 612 moveto 288 180 lineto 288 396 moveto 136 244 lineto 288 396 moveto 440 244 lineto 36 setlinewidth stroke showpage
pavlov@canisius.UUCP (Greg Pavlov) (02/25/91)
In article <4501@syma.sussex.ac.uk>, lezo@syma.sussex.ac.uk (Lez Oxley) writes: > > Data Compression Devices are now available for 8mm, 4mm and .5 inch SCSI > Tape Drives to enhance data transfer rates and to increase tape capacity > up to 4 times. Typically, it is claimed that an Exabyte cartridge could > now hold up to 6.6 gigabytes of data. > Boy, this is very tempting. But I am scared by the thought that, 5 years from now, I'll be asked to restore some crucial data from an old cartridge tape, my compression gizmo will have died and I couldn't get it fixed/rep- laced, and the cartridge will thus be useless. pavlov@stewart.fstrf.org
mark@hpcpbla.HP.COM (Mark Simms) (03/05/91)
With respect to 4mm devices, there are a lot of activities underway at the moment to define a standard recording format for compressed data. The final draft of ECMA/TC17 has been submitted to the European Computer Manufacturer's association. This defines the way in which compressed data should be stored by extending the DDS format to allow compressed data to be identified. If you are worried about the possibility of not being able to restore data in the future, I would wait for drives that support this standard to become available. At least two manufacturers are working on drives with on board compression, that implement this standard. These drives should be available later this year. Mark Simms ---------------------------------------------------------------------- Opinions expressed are my own and are not intended to be an official statement by Hewlett-Packard Company ---------------------------------------------------------------------- Name: Mark Simms Profession: Software Engineer Occupation: Research and Development Organization: Hewlett-Packard Computer Peripherals Division Unix-mail: mark%hpcpbla@hplb.hpl.hp.com ----------------------------------------------------------------------