Author: Dave Berry
Big Block Bypass Mode Improves QoS for Scale out Storage
After commuting in Silicon Valley for a few decades now, I can really appreciate all of the techniques that the IT industry has invented to improve Quality of Service (QoS) for data center infrastructure. After all, in the data center, like on our roadways, ever-increasing scale and density are the mother of all invention!
As an early Hybrid Toyota Prius adopter, I was able to use the carpool lane and laughed at everyone else while flying by and getting to work three times faster due to my privileged driving and the improved the overall QoS I was experiencing. Rules change with technology advancements; now I watch the new electric cars cruise by in my former spot, and it’s painfully clear that big trucks cause the bottlenecks, so maybe the solutions is to let them have the car pool lane!
Adaptec by PMC® Series 7 and Series 8 storage adapters have recently implemented a suite of performance tuning knobs to optimize the I/O path to best suit the needs of specific applications. These parameters can adjust the adapter characteristics to achieve the best possible application performance without loading any new software versions or causing significant downtime.
One of these new features is called the Big Block Bypass mode, which is useful for deploying Simple Volumes in environments oriented towards cloud storage where:
- Files are greater than or equal to 64MB;
- Data protection methods don’t include RAID; and
- There are multiple levels of file systems.
In these cases, the desire to stream large files may be compromised by the management of multiple layers of file system metadata in scale-out object and block storage clusters. In Big Block Bypass mode, large writes go directly to media, while small blocks are caught in the cache. The result of capturing the small random writes in the cache dramatically improves the streaming of these large files within the cluster. In other words, it’s like letting the trucks have their own lane.
Stay tuned for my next posts on storage software features, where we’ll get into the benefits of cache preservation and striping.
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