I wanted to write a little something about DAS Cache. You may not have heard of it. In fact, Unless you purchase a Dell Server, you may not ever be exposed to it. Apparently, When you purchase a Dell Server, you may purchase an application called Das Cache.
Please be advised the support for this product is available only if you have a Pro Support Contract with Dell. See the sales information on this product here.
“San Disk DAS Cache software is fully supported by Dell Services and available with the purchase of a next-generation Dell Power Edge server”
Tell Dell Support you have Das Cache
After Spending a little time with this product, the main support incident happens when the support person is not told that Das Cache is installed on the system. The fact is this product is simple and will not likely fail. But, the key point is when Das Cache is Deployed, It takes the Place of windows, in terms of manageability and control.
What happens is either the IT person or the support agent treats this disk as a Windows Disk, trying to run operations on the disk directly. You can’t treat a DAS Cache Disk as a windows disk. I am thinking, this first fact is the cause of Support-ability problems with the product.
Use the Das Cache GUI
The Gui of Das Cache is simple. You simply select a Disk to use as the scratch disk, and a volume, which serves as your data volume. Das Cache keeps copies of the most used data, on an SSD Drive. I found that it doesn’t have to even be SSD. It could be just two Sata Jbod Disks.
The way you set this product up Is you select “add Cache” at the right side of the application window. You select disk 1, then disk 2, and finish. The product is now using Disk1 as a cache for the data volume Disk2.
If you want to do anything to that data disk, or the cache disk, the only option you have is to use the GUI, and assign or un-assign cache from the cache tab:
Or you may stop or start acceleration from the volumes tab:
The only other thing you can really do is reset performance statistics or Build an Incident report. This menu is off to the right hand side, of the GUI interface.
What troubleshooting vs. recreate Cache
In all honesty, the amount of troubleshooting that can be done on this simple product, is very limited. The danger of this product is if you try to go into windows and do things to this disk. Instead of doing that, you can just come into the DAS Cache GUI, stop accelerating, and then removing caching. Then you can come in and create the same cache, and choose start accelerating. That should be the extent of troubleshooting.
Most Common errors
My understanding is the most common errors with this technology is File Server Resource Manager errors. For example, here are some known issues with FSRM.
In reviewing File server resource manager, My advice would be to disable it and find out if the errors stop. If they do, then, it would be a question of disabling specific settings in FSRM to find out, what setting is incompatible.
I could see certain aspects of FSRM not being happy with Das Cache. On the other hand, these errors are likely false positives, as the Cache itself is not part of the actual File Storage system. As long as the Cache is working. I would say you just have some erroneous errors to contend with.
In the most extreme, you should just stop caching, stop accelerating, and perhaps re-configure the cache. The only reason this technology would have any trouble is if you made changes to the disk inside windows. Just make sure you use the DAS Cache GUI only, and you will be fine to troubleshoot with that only.
To troubleshoot with windows, you should remove caching and acceleration, to troubleshoot the disk, by itself.
In conclusion, I hope this is helpful, if you have to take this your support team, just make sure the first thing you tell them is you have a Das Cache setup. That is an important point. Otherwise, that leaves the support team looking at, what they think is a Windows disk, with some very unusual failures.
#I work for Dell Services.