On 11/09/15 12:26, jstacey wrote: > I recently enabled encryption in my bacula-fd.conf with these > entries: > > PKI Signatures = Yes PKI Encryption = Yes PKI Keypair = > "/etc/bacula/client.pem" PKI Master Key = "/etc/bacula/master.cert" > > The encryption works but now my LTO4 tapes can only store around > 812MB instead of the usual 1.2 -> 1.4 TB Is this normal? I might > enable gzip software compression but this is going to take a chunk > out of my CPU. I read that it is also possible to enable hardware > encryption on the drive. Maybe this method would allow me to keep > using hardware compression? Thanks
This is inherent in how encryption and compression work. Any good encryption process should emit ciphertext that contains as little as possible redundancy, because redundancy opens up possible methods to attack the ciphertext. However, compression *relies upon* redundancy. With no redundancy, compression cannot work. So ciphertext is generally incompressible. On the other hand, eliminating as much redundancy as possible from cleartext before encrypting it effectively strengthens the encryption. So, if you are going to both compress AND encrypt, FIRST compress, THEN encrypt. If you encrypt first, you won't be able to compress the result. So if you're going to use software encryption, and also want to use compression, you must use software compression *before* the encryption stage. You will not be able to employ hardware compression on already-encrypted data. There should be very little to no redundancy left to compress out. -- Phil Stracchino Babylon Communications ph...@caerllewys.net p...@co.ordinate.org Landline: 603.293.8485 ------------------------------------------------------------------------------ Presto, an open source distributed SQL query engine for big data, initially developed by Facebook, enables you to easily query your data on Hadoop in a more interactive manner. Teradata is also now providing full enterprise support for Presto. Download a free open source copy now. http://pubads.g.doubleclick.net/gampad/clk?id=250295911&iu=/4140 _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
