Tape Redirector questions

Blue407 · Tue Jul 29, 2014 9:04 pm

Hi All

I have just installed your free Tape Redirector on a 2012 host server and its working fine with a 2012 R2 VM. (Great bit of software Guys

and free to boot!)

I have seen some posts on the internet where there is a recommendation to adjust some iSCSI initiator properties, such as MaxRecvDataSegmentLength and MaxTransferLength etc.

Could somebody please confirm if this is still the case with Server 2012 and 2012 R2?
I've checked the registry of both the server and VM and neither have any of these values set by default.

Any advice or help gratefully appreciated as I want to get the maximum performance I can out of this solution.

Tue Jul 29, 2014 9:37 pm

(It's a StarPort forum so I'll move the thread to appropriate place)

Yes, you still have to set these keys or MSFT will send requests bigger port driver controlling tape can accept.

Yes, you have to create them if they are missing.

Blue407 wrote:Hi All

I have just installed your free Tape Redirector on a 2012 host server and its working fine with a 2012 R2 VM. (Great bit of software Guys and free to boot!)

I have seen some posts on the internet where there is a recommendation to adjust some iSCSI initiator properties, such as MaxRecvDataSegmentLength and MaxTransferLength etc.

Could somebody please confirm if this is still the case with Server 2012 and 2012 R2?
I've checked the registry of both the server and VM and neither have any of these values set by default.

Any advice or help gratefully appreciated as I want to get the maximum performance I can out of this solution.

Blue407 · Wed Jul 30, 2014 7:08 am

Thanks for the fast response.

Could you please confirm for me exactly what they are and if I need to set them on the physical host or VM server?
Is it normal for them not to exist? If that's correct what type of value should I create? DWord strings?

Wed Jul 30, 2014 8:23 am

You set them on VM where iSCSI initiator runs. You need to limit request sizes.

Yes.

DWORDs

Blue407 wrote:Thanks for the fast response.

Could you please confirm for me exactly what they are and if I need to set them on the physical host or VM server?
Is it normal for them not to exist? If that's correct what type of value should I create? DWord strings?

Blue407 · Wed Jul 30, 2014 8:58 am

To confirm, its these:-

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e97b-e325-11ce-bfc1-08002be10318}\0001\Parameters\

MaxRecvDataSegmentLength 524288

MaxTransferLength 524288

FirstBurstLength 524288

MaxBurstLength 524288

After that you need to modify the appropriate parameters in the Tape Redirector (Select server->Configuration Tab->Advanced settings)

Does it need a restart to take effect? Both the VM and Physical?

Wed Jul 30, 2014 10:12 am

You probably need to set values smaller. 128KB or even 64KB.

Yes reboot is req'd.

Blue407 · Wed Jul 30, 2014 10:26 am

Ok,so change all of them from 524288 to 65536?

The 524288 value was form a post I found on-line by one of your technicians/consultants.
Is there anything else I can tweak to improve performance/speed?

At the moment I am unsure where the bottleneck is using BackupExec 2014 but I want to make it as fast as possible to keep my backup window small.

Wed Jul 30, 2014 10:30 am

Experiment with a different values. Biggest ones will give better performance.

Blue407 wrote:Ok,so change all of them from 524288 to 65536?

The 524288 value was form a post I found on-line by one of your technicians/consultants.
Is there anything else I can tweak to improve performance/speed?

At the moment I am unsure where the bottleneck is using BackupExec 2014 but I want to make it as fast as possible to keep my backup window small.