Ok, we got feedback from Dell. Source of the desaster seems to be a communication problem between the PERC raid controller and the Lite-On SSDs which in certain conditions results in the controller turning one of the two SSDs off. DAS Cache somehow notices this and takes the cache offline without further notification. There is a firmware update for the PERC controller, which according to DELL might prevent the problem from reoccuring. Another firmware update for the Lite-ON SSD firmware is scheduled to be released in April 2015. We have decided to leave the SanDisk DasCache software turned off until both firmware updates are available and installed.
Hi, we're using SanDisk DASCache on our new PowerEdge R530 to accelerate a RAID5 Volume by means of two SSDs forming a RAID 1 SSD cache. Last night, around 5 o' clock p.m., the cache became suddenly unavailable, leaving the accelerated volume in an unaccessible state. On that volume we hosted three virtual servers, among them our primary DC, so this was a real critical incident. As we were unable to get helpful support neither from DELL nor from SanDisk, the only possibility we saw was to unblock and reformat the volume and then restore the virtual machines from our the weekly backup. The servers are now back up, but we're still busy cleaning up the mess. For now, we have disabled SanDisk DASCache. Has anybody made similar experiences with SANDisk DASCache in PowerEdge Servers? The version number of DASCache 1.1.1 suggests that the product might not be in the state of reliability that would be desirable for productive environments. Thanks for your comments and replies. Bernd  
DASCache crashed volume