How to set target parameters like "MaxBurstLength"

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iscsi_is_cool
Posts: 2
Joined: Mon Apr 25, 2005 2:19 pm

Mon Apr 25, 2005 2:32 pm

Hi there,

while evaluating StarWind with initiators on Linux and Windows boxes I noticed that the StarWind log contains entries with which parameter values the initiators are connecting to the targets.

As far as the Linux initiator is concerned I could quite easily set the parameter values in the initiator's config file.

The initiator connects to the target with these values but the target just takes some default settings and not the ones the initiator want's to use (e.g. "Numeric param 'MaxBurstLength': received 16776192, accepted 262144").

I'm quite sure that setting these params on the target side would result in a noticeable performance boost for the iSCSI connections.

Is there a way to set these parameters, e.g. in the StarWind config file? If so, are these settings being made on a "per server" or a "per target" basis?

Bye
Sepp


PS:
Are you planning to make all of the advanced settings available via the StarWind GUI, or will I have to type them manually into the config file and restart the service to enable the new settings?
Val (staff)
Posts: 496
Joined: Tue Jun 29, 2004 8:38 pm

Mon Apr 25, 2005 3:36 pm

hi Sepp,

MaxBurstLength:
Default is 262144 (256 Kbytes).
Result function is Minimum.

StarWind uses 256K as its default value. So it supports MaxburstLength values up to 256k.

For example, Windows initiators use 64K requests in 99% of cases.

You are the first person who asked us about enlarging MaxburstLength. If you really need this we could add the parameter to StarWind configuration.

The recent SarWind GUI allows only freaquently used parameters to be modificated. Yes, we have plans to enhance the GUI.
Best regards,
Valeriy
Guest

Tue Apr 26, 2005 7:54 am

Hi Valery,

thanks for the quick response.

I think it would indeed be nice if one could change the iSCSI target parameter settings. I asked for this because I can change this settings in the Linux initiator I'm using (the one you could find at http://sourceforge.net/projects/linux-iscsi).

Are there, from your experiences, any settings in Win2k3 Server (not in StarWind) that could improve the iSCSI performance?

Your product is good, and I will use it for the SAN environment I'm currently building. But any improvements in performance, GUI etc. are highly appreciated.

Bye
Sepp
Val (staff)
Posts: 496
Joined: Tue Jun 29, 2004 8:38 pm

Tue Apr 26, 2005 10:51 am

Hi Sepp,

Thank you for the idea. We'll implement the iSCSI parameter configuration in the next StarWind release.

According to tuning of a Windows 2000/XP/2003 machine for iSCSI performance:

You need change the following TCP parameters in the registry:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]

1) GlobalMaxTcpWindowSize = 0x01400000 (DWORD)
2) TcpWindowSize = 0x01400000 (DWORD)
3) Tcp1323Opts = 3 (DWORD)
4) SackOpts = 1 (DWORD)

And restart the machine.
Best regards,
Valeriy
iscsi_is_cool
Posts: 2
Joined: Mon Apr 25, 2005 2:19 pm

Wed Apr 27, 2005 11:40 am

Hi Valery,

thanks for these settings, I'll try them once I could reboot my storage server.

Another questions:

Does StarWind benefit from using a TCP Offload Engine (TOE)? This would be a good tradeoff, being much cheaper than iSCSI HBAs or even an FC based SAN.

Bye
Sepp
Val (staff)
Posts: 496
Joined: Tue Jun 29, 2004 8:38 pm

Wed Apr 27, 2005 11:59 am

StarWind v2.x is a pure Windows usermode service.
It uses only standard TCP/IP APIs. So it definitely benefits from using a TOE especially when a 1GbE+ adapters are used.
Best regards,
Valeriy
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