Increasing VMWare SCSI Timeout on RHEL6 and ESX5

VMWare recommends increasing the disk timeouts for linux guests to 180 seconds to handle things like a storage path failover. There are a few ways to accomplish this. If you are a Netapp customer you could run their script, or you could follow the instructions in the VMWare article.

Unfortunately, both of these solutions were written for ESX4 and RHEL5. If you are on ESX5 with a RHEL6 guest, do the following to increase your timeout for VMWare SCSI disks to 180 seconds:

1. Put the following in a file in /etc/udev/rules.d. I chose /etc/udev/rules.d/99-vmware-scsi-timeout.rules.
   SUBSYSTEM=="block", ACTION=="add", BUS=="scsi", SYSFS{vendor}=="VMware", SYSFS{model}=="Virtual disk",   RUN+="/bin/sh -c 'echo 180 >/sys$DEVPATH/device/timeout'"
2. Run udevadm test /block/sda and make sure you see a line that indicates the echo 180 would run. If it doesn't then your SYSFS values are somehow different than mine. The output you just got should help you figure out the correct values. Look for the entries that start with ID_.
3. Once you have udevadm telling you it would run the echo 180 command you can restart your machine or restart udev during your maintenance window, if this is a production VM. If you don't want to reboot the machine, you can restart udev with:
1. udevadm control --reload-rules
2. start_udev
4. Verify it worked by looking at the timeout file in the /sys tree for your devname. For me this was accomplished with: cat /sys/block/sda/device/timeout