The whole compression issue has always confused the hell out of me (no certification here :-). Does 200-400 mean "200-native-,-400-if-we-hardware-compress-as-we-stream-to-tape"? Sometimes the client may also compress? I think salespeople over the years have greatly abused this x-2x tape cartridge capacity thing to their advantage - you can always double up because nobody knows what you're talking about anyway.
And you mean LZ (Lempel-Ziv) algorithm, don't you :-? ------------------------------------------- Willem Roos - (+27) 21 980 4941 Per sercas vi malkovri > -----Original Message----- > From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] > On Behalf Of Christo Heuer > Sent: 16 April 2004 09:26 > To: [EMAIL PROTECTED] > Subject: Re: LTO tape cartridge(200GB/400GB) stores data 500GB+. > > > It depends on the actual type of data - take a 2Tb oracle db > that is mostly > empty you will be getting a 90%+ compression ratio - so your > LTO-2 cartridge > will show the capacity used as 2000Gb. > The typical ratio IBM used to qoute was 3-1 in recent years > they changed > this to 2-1, > hence the 200-400 figure. The algorithm used for the comression is a > modified ZL algorithm - similar to the algorithm used for pkzip etc. > If you send already compressed data your tape usage will show > 200Gig or > less - if you were getting negative compression ratios - data already > compressed can grow if comressed again. > So - there is no clear-cut answer - work on the native > capacity(200G), and > everything else you get is a bonus. > > Cheers > Christo > ----- Original Message ----- > From: "Chandrashekar, C. R. (Chandrasekhar)" > <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Friday, April 16, 2004 7:50 AM > Subject: Re: LTO tape cartridge(200GB/400GB) stores data 500GB+. > > > > This is not a puzzle for me, Actually I want to know how > much data it can > > compress, Is there any one using same tape library. Which helps to > estimate > > the total storage capacity. > > > > Just to know how much percentage of compression in 3583L23 > library using > > 3580ULTGen2 drive. > > > > Thanks, > > c.r.chandrasekhar > > > > -----Original Message----- > > From: ADSM: Dist Stor Manager > [mailto:[EMAIL PROTECTED] Behalf Of > > Christo Heuer > > Sent: Friday, April 16, 2004 10:51 AM > > To: [EMAIL PROTECTED] > > Subject: Re: LTO tape cartridge(200GB/400GB) stores data 500GB+. > > > > > > Hi, > > > > I see you are a Tivoli certified consultant (TSM) - maybe > they missed that > > part in > > the certification exam - why don't you read up on > compression - if this > > puzzles you > > I'm sure plenty other things will confuse the hell out of you. > > > > Christo > > ----- Original Message ----- > > From: "Chandrashekar, C. R. (Chandrasekhar)" > <[EMAIL PROTECTED]> > > To: <[EMAIL PROTECTED]> > > Sent: Friday, April 16, 2004 6:51 AM > > Subject: LTO tape cartridge(200GB/400GB) stores data 500GB+. > > > > > > > Hi, > > > > > > Just for clarification, I'm using LTO-Ult tape cartridge > having capacity > > of > > > 200GB/400GB, Tape library 3582L23 with two 3580-LTOG2 drives with > firmware > > > 38D0, and devclass was defined with device-type=LTO and > Format=ULTRIM2C. > > Now > > > the tape is storing more then 500GB of data, Is it normal > behavior. > > > > > > Thanks, > > > CRC, > > > > > > C.R.Chandrasekhar. > > > Systems Analyst. > > > Tivoli Certified Consultant (TSM). > > > TIMKEN Engineering & Research - INDIA (P) Ltd., Bangalore. > > > Phone No: 91-80-51362222. > > > Email:[EMAIL PROTECTED] > > > > > > > > > > > > > > > > ********************************************************************** > > > PLEASE NOTE: The above email address has recently changed from a > previous > > naming standard -- if this does not match your records, > please update them > > to use this new name in future email addressed to this individual. > > > > > > This message and any attachments are intended for the > > > individual or entity named above. If you are not the intended > > > recipient, please do not forward, copy, print, use or > disclose this > > > communication to others; also please notify the sender by > > > replying to this message, and then delete it from your system. > > > > > > The Timken Company > > > > ********************************************************************** > > > > ______________________________________________ > > E-mail Disclaimer and Company Information > > > > http://www.absa.co.za/ABSA/EMail_Disclaimer > > > > > > > ********************************************************************** > > PLEASE NOTE: The above email address has recently changed > from a previous > naming standard -- if this does not match your records, > please update them > to use this new name in future email addressed to this individual. > > > > This message and any attachments are intended for the > > individual or entity named above. If you are not the intended > > recipient, please do not forward, copy, print, use or disclose this > > communication to others; also please notify the sender by > > replying to this message, and then delete it from your system. > > > > The Timken Company > > > ********************************************************************** > > ______________________________________________ > E-mail Disclaimer and Company Information > http://www.absa.co.za/ABSA/EMail_Disclaimer
