- The FC connection dropped a packet somewhere between the Host Bus Adapter (HBA) and the storage array.
- The array controller or a device in the array responded to an I/O request and indicated that the hardware exceeded hardware-defined time-outs in the array.
Disk Event 154 is a new system event in Windows Server 2012 that is intended to log cases in which an FC packet may have been dropped. The intention is to make these issues more discoverable. A dropped FC frame can have a large effect on user experience, because the time that the operating system will wait for an I/O operation to finish is based on the disk.sys TimeOutValue value, and the operating system may seem to be frozen or to hang while it waits for the I/O operation to finish. After the time-out value is reached, the disk/class layer will retry the I/O operation eight times. (Each attempt waits the full amount of the TimeOutValue value).
Currently, we recommend that you set the disk.sys TimeOutValue value as low as possible. (We recommend that you set it to a value no greater than 20 to 30 seconds). However, as with any change, the value that you use should be evaluated in a test environment before you implement that value in production.
The value is global. Therefore, avoid very short time-out values. Otherwise, you may experience time-out errors in scenarios such as when you are waiting for a sleeping disk or DVD drive to spin up.
For more information, see the following blog post:
To set the disk.sys TimeOutValue value, follow these steps:
- Start Registry Editor. To do this, click Start, type regedit in the Start Search box, and then press Enter.
- Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk
- Locate TimeOutValue.
- On the Edit menu, click Modify.
- In the Value data box, type the desired number of seconds.
- Exit Registry Editor.
Article ID: 2806730 - Last Review: Jan 29, 2013 - Revision: 1