I have a customer that has a 1/2 Rack Exadata and a ZFS7420 with two trays, each with 24 3TB Disks. All 24 disks in a big RAID5 set.
We can get 2TB/h and he wants to get 4TB/h. According to the Whitepaper about using ZFS to backup Exadata, you can get 8TB/h with 4 trays.
What I found is that each disk has 150BM/s transfer rate according to Seagate. Since each tray has a SAS-2 path, that has 6Gb/s transfer rate, this should be around 600MB/s. So with only four 3TB disks I can saturate one full tray transfer rate.
Is this correct ? Or the SAS-2 is dual ported with two SAS buses and I can get twice that per tray ?
If I use mirro I will have half the transfer rate, since I need to write twice the same data. Is this correct ?