>> On Thu, 12 Jul 2007 07:32:27 -0500, Andy Huebner <[EMAIL PROTECTED]> said:
> To me it is not the incoming, but the outgoing that is the greatest > concern. If the next pool is physical tape, be sure you have enough > speed to keep up with your tape drives. If the disks cannot keep up > with the physical tape drives then performance will not be acceptable. > Since many VTLs use ATA disks we know it can be done. This is a really good point. Keeping the number of read streams under control will make a huge difference in your performance. When I drain a SATA pool with a single thread, I can drive one of my 3592s at 80-90 MB/s. When I put three of them on the job, aggregate throughput drops to ~30 MB/s (yes, each drive getting ~10MB/s). - Allen S. Rout
