Last week Apple pushed out a combined OS X Lion and security update. It's still being pushed out through the Software Update service. While most third-party applications appear to be playing well with the update, a number of serious compatibility issues have been reported, including problems mounting external SATA drives and software RAID volumes.
OS X Lion v10.7.4 Update appears to have a number of attractive fixes for users in a Windows server environment, including improved reliability of binding and logging into Active Directory accounts, and when connecting to a WebDAV server. It appears to fix a longstanding bug for issues that may prevent files from being saved to an SMB server.
Details on the security portion of the update can be found here.
However, a number of storage vendors have reported problems with mounting external SATA storage following the update. In a Macintouch post, a Sonnet Technologies tech advised customers to wait on the update based on a number of support calls. However, the company hadn't been able to replicate the issue.
Mark James of SoftRAID also posted on Macintouch saying that his company started receiving reports of SoftRAID volumes not mounting following the update. The company had then received reports of Apple RAID volumes also failing to mount.
However, we have identified the likely source of the problem through the kernel.log file. The file system is failing to mount the [volume]. If you encounter this problem (your RAID volume is not mounting), open the Kernel.log file in the Console.app and filter for "45"; you should see strings indicating "hfs_mountfs: buf_meta_bread failed with 45". There are also entries with "unsupported function" when the OS tries to mount the volume. We are investigating this, and do not yet have a solution. We want to alert all Lion users who use RAID (or PGP), do not update Lion to 10.7.4 until there is a published fix for this problem.
Some products that weren't certified to run under OS X Lion but that had, now may break under the OS X Lion v10.7.4 Update. This may be with Java security tightening in the update. Some of these titles were detailed in the Macintouch discussion.
Some users may have been running VMWare Fusion 2.0.x under OS X Lion 10.7.3 or earlier, however, the end of the road is the latest update from Apple. Of course, the latest Fusion 4.1.2 is fully Lion compatible. VMWare certifies Version 3.x for Snow Leopard and Leopard but Version 3.1.3 will run Lion with some caveats explained in this Knowledge Base article.