Is it still true that the client side compression requires paging in the whole object before it can be compressed?
Tying up 10GB of RAM and/or paging/swap space (or more in the case of larger objects) used to be a big enough concern to recommend against the practice. Especially on Windows where memory was so constrained, and using up available RAM tended to cause the app to die. [RC] -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[email protected]] On Behalf Of Rainer Wolf Sent: Wednesday, March 18, 2009 8:35 AM To: [email protected] Subject: [ADSM-L] is TSM Client-encrypted data still compressable on the 3592 Drives ? Hi All, we normally recommend 'not using TSM Compression' becaus the fantastic 3592-drives are doing the compression very well and fast. If users want to encrypt their data with the tsm-client I tend to recommend also using compression because data would be first get compressed and then get encrypted (on the client). This should help save some space on the tapes but it is only an assumption and possibly compression is not essential. my question is If I have a 10GB file and this would appear (without Client-compression and without client-encryption) as 6GB on the tape (after the hardwarecompression) ... ... is it possible to say something about what happens if I set up TSM Encryption (AES128) and send this file again - now encrypted ? Wil this data appear more at around 6GB, more at around 10GB, somewhere between ? Or is it something completely unpredictable ? Statistics would be also interesting If it is more at 10GB it makes sense using TSM client-compression just to save space. Because of the recently discussed problems with restoring tsm-compressed data that is aleady compressed by any software then the comressalway-Option shouldn't also be used there to avoid problems at restore-process ? thanks in advance for any hints Rainer -- ------------------------------------------------------------------------ Rainer Wolf eMail: [email protected] kiz - Abt. Infrastruktur Tel/Fax: ++49 731 50-22482/22471 Universitaet Ulm wwweb: http://kiz.uni-ulm.de DISCLAIMER: This message is intended for the sole use of the addressee, and may contain information that is privileged, confidential and exempt from disclosure under applicable law. If you are not the addressee you are hereby notified that you may not use, copy, disclose, or distribute to anyone the message or any information contained in the message. If you have received this message in error, please immediately advise the sender by reply email and delete this message.
