> On 11/09/16 10:56, Alan Brown wrote: >> On 09/11/16 14:17, Ralf Brinkmann wrote: >>> I just checked the use of the multicore compression program "gzip" on >>> one file-daemon side. It did use 32 cores out of 48 possible. >>> >>> I think even for LTO tape drives the use of a multicore compression tool >>> could be a win on time and storage space. >> Be sure that that your "48 cores" really are physical cores - >> hyperthreading is of no use when running gzip processes and using more >> pigz threads than there are physical CPUs will result in performance loss. >> >> Pigz -9 will normally get you 5% extra over the onboard hardware >> compression on a LTO drive, with a massive computational cost - and you >> have the extra cost of getting the data in from a PCIe bus, processed >> through the CPU(s), and out through another PCIe bus, with the overall >> penalties meaning it's simply not worth doing it. > > Also consider that LTO drive hardware compression is smart. When it > receives a block to be written to the tape, it makes a compressed copy > of the block, compares the size of the compressed and uncompressed > blocks, and writes *whichever is smaller* to tape. Software compression > on the host does not do this. > > Really, LTO compression is so good that there is no defensible reason > not to use it.
Hello, Alan, Ralf, Phil: pgzip would be nice for disk backup storage and huge uncompressed files copy (e.g.: VM exports, DB dumps etc.), but there is no reason to replace hardware tape native virtually no downside compression for any software one (IMHO). Regards, -- =========================================================================== Heitor Medrado de Faria - LPIC-III | ITIL-F | Bacula Systems Certified Administrator II • Do you need Bacula training? http://bacula.us/video-classes/ +55 61 8268-4220 | http://bacula.us =========================================================================== ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today. http://sdm.link/xeonphi _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
