AX4 Performance

You can monitor disk performance in win by perfomance monitor, on array side you can monitor by Navisphere Analyzer if you have it.
Cache enabled on array?

I'm getting pretty good performance on mine, so I'd think it might be a setting or configuration issue.

You might want to look more at the NIC and Switch. Make sure you have optimized them for iSCSI traffic and preferably it's seperate from your normal network traffic. Make sure all the netwrok settings are right like enabling TOE, enable jumbo frames, enable flow control, disable unicast storm control, and disable spanning-tree for iSCSI traffic. I've used IOMeter to test disk performance before.

You can also view the properties of the SPA and SPB as well as the properties of the LUN's you want to monitor. It's sort of real time (every 30 or 60 seconds the numbers change and what you're seeing are the MBps (read and write) and IOps (read and write).

iSCIS Performance issues

EMC has found that there are two Windows registry settings that can impact performance for Windows 2000 and Windows 2003. If setup your host using the Navisphere Server Utility (NSU), both of these settings will be set (if you select the performance check box). If you did not use the NSU, but did install Navisphere Agent, the second registry setting will be set (Tcp1323Opts).

You can check by examining the registry.

Please see KnowledgeBase article emc150702 ¿ this is for the TCP Delayed ACK issue

http://knowledgebase.emc.com/emcice/documentDisplay.do;jsessionid=82BFA69668D872432926C476D516E981?docType=1006&clusterName=DefaultCluster&resultType=5002&groupId=1&page=&docProp=$solution_id&docPropValue=emc150702&passedTitle=null

The other setting is called Tcp1323Opts ¿ this should be set to a value of 2, default is 0:

Tcp1323Opts
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Data type Range Default value
REG_DWORD 0 | 1 | 2 | 3 0

Description

Determines whether TCP uses the timestamping and window scaling features described in RFC 1323, TCP Extensions for High Performance.
Window scaling permits TCP to negotiate a scaling factor for the TCP receive window size, allowing for a very large TCP receive window of up to 1 GB. The TCP receive window is the amount of data the sending host can send at one time on a connection.

Timestamps help TCP measure round trip time (RTT) accurately in order to adjust retransmission timeouts. The Timestamps option provides two timestamp fields of 4 bytes each in the TCP header, one to record the time the initial transmission is sent and one to record the time on the remote host.
This entry is a 2-bit bitmask. The lower bit determines whether scaling is enabled; the higher bit determines whether timestamps are enabled. To enable a feature, set the bit representing the feature to 1. To disable a feature, set its bit to 0.

Value Meaning
0 (00) Timestamps and window scaling are disabled.
1 (01) Window scaling is enabled.
2 (10) Timestamps are enabled. <----- use this setting for iSCSI
3 (11) Timestamps and window scaling are enabled.

Note

Windows 2000 does not add this entry to the registry. You can add it by editing the registry or by using a program that edits the registry.

glen

Do you have any clue on what kind of result the IO meter should give me when used for a AX4 iSCSI installed on Windows 2003 host with dual NIC and direct connect...no network switches in between?

I am not able to open this link...perhaps I don't have the access. Can you post the article here?

If you go tot PowerLink and choose:

Home > Support > Knowledgebase Search > Support Solutions Search

and type in emc150702

Slow performance may occur during network congestion when RFC 1122-delayed acknowledgements extend the error recovery process. In these situations, the default 200 millisecond delay on the acknowledgement cansignificantly impact read bandwidth. PowerPath, by load balancing read requests across multiple array ports, increases the likelihood that simultaneous read completions from multiple ports will result in network congestion. This increases the likelihood of experiencing the problem.
As specified in RFC 1122, Microsoft TCP uses delayed acknowledgments to reduce the number of packets that are sent on the media. Instead of sending an acknowledgment for each TCP segment received, TCP in Windows 2000 and later takes a common approach to implementing delayed acknowledgments. As data is received by TCP on a particular connection, it sends an acknowledgment back only if one of the following conditions is true:

* No acknowledgment was sent for the previous segment received.

* A segment is received, but no other segment arrives within 200 milliseconds for that connection.

Typically, an acknowledgment is sent for every other TCP segment that is received on a connection unless the delayed ACK timer (200 milliseconds) expires. You can adjust the delayed ACK timer by editing the registry as outlined in the workaround below.

Fix:

Modify the TCP/IP settings for the network interfaces carrying iSCSI traffic to immediately acknowledge incoming TCP segments. This workaround solves the read performance issue. The procedure to modify the TCP/IP settings is different for Windows 2000 servers and Windows 2003 servers. Follow directions appropriate for the version you are running on your servers.

These setting are MANDATORY for all Microsoft iSCSI clusters and are RECOMMENDED for all Microsoft iSCSI configurations.

Microsoft iSCSI clusters also require array software revision 3.22.xxx.5.511 or 3.24.xxx.5.007 or later.

Note: These TCP/IP settings should not be modified for network interfaces not carrying iSCSI traffic as the increased acknowledgement traffic may negatively affect other applications.

Caution! This workaround contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following link to view the following article in the Microsoft Knowledge Base: http://support.microsoft.com/kb/256986/.

On a server that runs Windows 2000 SP3 or later, follow these steps:

1. Start Registry Editor (Regedit.exe).

2. Locate and then click the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces

the interfaces will be listed underneath by automatically generated GUIDs like {064A622F-850B-4C97-96B3-0F0E99162E56}

3. Click each of the interface GUIDs and perform the following steps:

a. Check the IPAddress or DhcpIPAddress parameters to determine whether the interface is used for iSCSI traffic. If not, skip to the next interface.

b. On the Edit menu, point to New and then click DWORD value.

c. Name the new value TcpDelAckTicks and assign it a value of 0.

4. Exit the Registry Editor.

5. Restart Windows for this change to take effect.

On a server that runs Windows Server 2003 SP1 or later, follow these steps:

1. Start Registry Editor (Regedit.exe).

2. Locate and then click the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces

the interfaces will be listed underneath by automatically generated GUIDs like {064A622F-850B-4C97-96B3-0F0E99162E56}

3. Click each of the interface GUIDs and perform the following steps:

a. Check the IPAddress or DhcpIPAddress parameters to determine whether the interface is used for iSCSI traffic. If not, skip to the next interface.

b. On the Edit menu, point to New, and then click DWORD value.

c. Name the new value TcpAckFrequency, and assign it a value of 1.

4. Exit the Registry Editor.

5. Restart Windows for this change to take effect.

Note: A more user-friendly method of changing the registry setting is now included in the Server Utility for Release 24 patch (6.24.1.4.0) as an option to "Optimize the Network." See the linked screen capture. This may be an easier fix for some customers than manipulating the registry directly and the registry change is set for the correct iSCSI network.

glen

What is the model number of the AX4? Is it an AX4-5SCi? Single processor AX arrays do not have Write cache and Writing will be slower than Reading.

glen