we are currently experiencing very slow speeds when copying a huge file (35GB+), to our surprise it starts off at a very high transfer rate 300MB/s, then drops to 4MB/s after 10-20 seconds into the transfer. the file is being transferred from the iSCSI LUNs to the local drives on the machine, also tried to copy the file to /dev/null results are the same, there is a 1Gbs link going into the target, target, switch and initiator are all on a private VLan, the MTUs are also set at 9000 on all three components.
can anyone help us understand why the transfer suddenly goes down to 4MB/s?
thank you for your time.
Storage is NETAPP FAS2040, RHL 5.2, CISCO Switches.