1. Yes. Trying to compress an already compressed file can cause the file to grow larger. 2. No. We run a 3494 Magstar - hardware compression is ALWAYS on, you can't override it. It is controlled within the hardware and our ZOS system. 3. Prevent - No. Degrade or hinder - Yes, it can.
-----Original Message----- From: Wholey, Joseph (TGA\MLOL) [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 31, 2002 1:05 PM To: [EMAIL PROTECTED] Subject: Re: Antwort: Re: low bandwitdth and big files Nick, I have client compression turned on also due to slow network (have no choice). But no one has been able to answer the following questions definitively: 1. Am I potentially doubling the size of certain files in the stg pool by running multiple compression algorithms.? 2. By turning off DEVCLASS compression, is that effectively disabling hardware compression performed by my tape device (IBM 3590 TAPE Device / Cartridge) 3. If client compression and hardware compression are turned on, and hardware compression isn't really buying me anything... won't the attempt at hardware compression prevent streaming? I think it will. I'm looking for YES/NO answers with a valid explanation. Anyone????? Regards, Joe -----Original Message----- From: Nicholas Cassimatis [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 31, 2002 1:32 PM To: [EMAIL PROTECTED] Subject: Re: Antwort: Re: low bandwitdth and big files A long while back, I had 36 boxes of the following config: Pentium 100's, 128MB RAM, 16Mbit Token Ring, running OS/2 2.11 with Lan Server 4, Notes 4.1, backing up mail files as flat files. Turned client side compression on, backup window went from 4 hours to 1.25 hours. I cut the data sent over the wire down by 66%, and got a corresponding reduction in the backup time. My machines were effectively offline for the backup window, due to the network being saturated, so the fact they were also CPU bound really didn't matter. It all depends on the config. The worst you could do is to test a little, see what happens. Oh, my library was a 3494 with 2xB11 drives in it. I kept utilizing the same number of tapes, but the capacity at full went from around 28GB to 11GB, as would be expected. Nick Cassimatis Technical Team Lead e-Business Backup/Recovery Services 919-363-8894 T/L 223-8965 [EMAIL PROTECTED] Today is the tomorrow of yesterday.
