RDS container limiting writing speed to LTO5 tape (4037116)

RDS container limiting writing speed to LTO5 tape

RDS container is limiting read speed from DR4100. Is the DR4100 performing the de-duplication or something else? 

The following tests were done.

Direct to tape at 110MBps
Data copy from tape to tape at 110MBps
Backup to DR4100 at 90~100MBps
DR4100 to tape at 28~30MBps

The maximum throughput is around 30MBps when we know that the LTO5 can go up to 140MBps. When tested with a different source container like NFS, the read speed reached to 30~35MBps.

The DR will re-inflate the data into its original undeduplicated form before it is transmitted to Disk, Tape, SmartDisk, etc 

This obviously has an overhead and could be affecting the data transfer rate.

Configure multiple streams in a datacopy job and check the read speed

The downside of this is that they need two drives and that the data will end up on two tapes so it's a more disruptive approach


Troubleshooting steps:

Check the below settings that might affect the transfer speed for both read & write speed

Note: Performance issue cases are very complex and the problem could be anything from the network, protocols, ports, the type of files etc, OS or hardware

1. Create a RDS 2nd container and perform a backup job to this container and record the write speed. Then perform a read job from that same container and read from this container and write to the local HDD on the host. Do you get the same speed?

2. Also test the read & write speed from DR. Create a CIFS container, if you perform a drag and drop files to and from the CIFS container, do you notice any read or write speed issues?

3. Check if the NIC cards in bonding on DR4100?

4. What is the model of the switch and how is the switch configured?

5. How is the network cabled up between the DR4100 and switch and host?

6. How are you measuring the performance or read/write speeds? 

7. Do get the same performance when reading from other containers?

8. Check and ensure the DR4100 is setup according to best practice below is the link for netvault 

https://support.quest.com/dr-series

Note: Please make sure the DR firmware is on the latest version (as there has been a number of fixes and enhancements included in the latest version)


If you still have issues with the read and write speed , Please get in touch with Technical Support to check for any issues on the DR4100.