On 14/08/09, Frank Smith (fsm...@hoovers.com) wrote: > Chris Hoogendyk wrote: > > Amanda will do the compression for you. You define it in the dumptype in > > amanda.conf. If you have a holding disk, then it will compress the data > > as it goes onto the holding disk. If you don't have a holding disk, then > > you might have issues with being able to stream a backup to tape, > > compressing it on the fly. Even with a really fast cpu, I don't know if > > you can maintain the throughput to drive LTO4 at a good speed. > > You might want to consider configuring for client compression. Not > only will that give you more CPU for feeding your tape, it also > minimizes network bandwidth. As usual, YMMV, it all depends on where > the bottlenecks are in your environment.
In our case the server _is_ the only client, with up to 30TB of direct attached storage, with the storage running at between 80MB/s and 120MB/s access speeds (Bytes rather than bytes). I don't know if this is fast enough to deal with a SAS connected LTO4 drive, particularly if it is doing software compression along the way. With reference to Chris Hoogendyk's email "clarification on parallelism", I am very curious to learn if Amanda "...still require[s] a DLE to be completed to holding disk before it will send any of it to tape..." In our case this is a particularly important question as, although we can add in more AoE storage for a DLE, this will only run at the speeds above. Do we need a 1TB SAS disk array too? Rory -- Rory Campbell-Lange Director r...@campbell-lange.net Campbell-Lange Workshop www.campbell-lange.net 0207 6311 555 3 Tottenham Street London W1T 2AF Registered in England No. 04551928