Mixed Flash? – What do you want that for?

When Dell Compellent first announced that we were going to be shipping an All-Flash array I don't think too many people were surprised, after all we have been shipping flash in our storage products for quite some time. What did surprise people was that we were going to ship an All-Flash Array that used both SLC (single level cell) and MLC (multi-level cell) flash types in our systems. The immediate question we heard was "why do you want to do that?"

The answer is really pretty simple; it allowed us to drive down the cost of our All-Flash Compellent Array so it was at the same price point of a high performance hard drive array. But as Storage Switzerland pointed out in its upcoming lab report "Mixed All-Flash Array Delivers Safer High Performance" this mixture of SLC and MLC allows us to deliver a safer, higher performing solution than our competitors.

We optimized the Compellent code for flash so that all inbound writes go to a RAID 10 based SLC tier of flash. This means your newest data goes to the safest form of flash, with the highest level of protection. In addition, SLC also delivers the highest level of performance, with write performance much higher than MLC.

To keep costs down, data is periodically and automatically moved via our Data Progression technology to the MLC tier. MLC is much lower cost per GB than SLC but can't sustain the write I/O load that SLC can. Data progression, other than the initial migration to MLC, turns the MLC tier into a read-only (mostly) tier, which means it will last much longer than in other configurations. Of course this tier is still protected by RAID, so a failure in a single SSD drive won't mean the loss of data.

The Fine Point

The fine point of the solution is that the All-Flash Array does more than just match a hard drive based system in price. It reaches this price point by delivering the safest, longest lasting flash deployment available in the industry today. At least that is my opinion.  To discuss the All-Flash Array and Storage Switzerland's report in more detail please join us for a live webinar at Noon Central US time on Tuesday, September 10th.

During this webinar Storage Switzerland's lead analyst George Crump and I will discuss the results of their lab study and the impact of the Dell All-Flash Array in customers’ data centers. As an added bonus I've talked George into sending an advanced copy of the report to webinar attendees upon registration. So head over to http://www.storage-switzerland.com/BTDellFls.html to get a copy of the report and register for the webinar.

About the Author: Bob Fine