I am running esxi on dell r610 machine. This error was not causing problem for production envoirnment but still want to resolve it as a premtive measures. Dont know what is causes that error and checked online and found none of any microsoft KB which is targeting 2008 server, only xp or 2003. and its appearing from last three days. Log Name: System Source: Disk Date: 8/4/2010 10:24:45 AM Event ID: 15 Task Category: None Level: Error Keywords: Classic User: N/A Computer: xxx.xxx.xxx Description: The device, \Device\Harddisk2\DR4, is not ready for access yet.

You may want to ask in the VMware forums first and then ask here if they cannot point you to anything, http://communities.vmware.com/home.jspa -- Mike Burr

Salman, I am receiving the exact same error and it began August 4, 2010 when your post went up. This issue is actualy causing my server to freeze or even reboot in to recovery mode sometimes. Were you able to determine the cause? My setup is much like yours. This is a Windows 2008 R2 OS on an ESX4 server. In my case, this is production and is causing us a lot of heart ache. Please let me know if you find a solution. Thanks. The device, \Device\Harddisk4\DR4, is not ready for access yet.

On almost all web forums this error is related to storage device or driver. At Vmware KB it was stated that this is a serious issue and integrity of VMFS colume can be compromised. And some on Microsoft KB suggested that you can safely ignore that issue. In our case this error isn't appearing from last two days. below are the steps which i found and performed. Step 1: VMWare Event generated when virtual machine is stored on a spanned VMFD colume that has one or more missing span members. Aricle http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1005204 discussed the error in detail. But before jump on to resolution, determine on which point at your envoirnment. Step 2: An online article also suggested to clear prefetch folder or disable it in the registry editor. Here is the article http://www.hardwareanalysis.com/content/topic/12946/?o=280 to prevent this error but it doesn't mean you are using esxi or not, but good to perform. Step 3: Run error-check on hard disk and also do defragmentation. Since most of the drive errors clears out in disk checking so I am suggesting that one on my own experience. After performing these all steps I didn't receive this error so far.

Salman, Thank you so much for your reply. I will begin working through your steps. I located the VMware doc earlier and have already begun working through that one. Thanks again for your detailed reply.