The impact of SSDs on I/O related performance in a server is dramatic. Unleashed from the mechanical limitations of spinning disks, a single server can perform 10s or 100s of thousands of I/O Operations per second, IOPS, instead of just a few thousand. Without long I/O waits, processor, RAM and RAID controllers can all get much busier, but the impact on humbler pieces of Continue reading SSD Performance has System-wide Effects
Or, How Many Eggs in One Basket? Huge storage systems are available today supporting large numbers of disks, allowing the creation of massive storage resources. Storage Servers and storage enclosures suporting up to (60) 3.5″ disk drives are now common. Filling those bays with 6TB disks yields a system with 360TB raw capacity – one third of a petabyte! That is now an easy Continue reading Storage Sizing for Capacity and Performance
If you have spent any time with computer benchmarks, you have probably heard the expression “Lies, damned lies, and benchmarks!” Why do people feel that way about benchmarks? Well, it is because many benchmarks have been presented with little or no context about what that benchmark really meant. “What was the hardware configuration?” “Was it running special firmware?” “How was the software tuned and Continue reading A Few Thoughts on Benchmarks
The title of this series of posts is “Spinning Rust is Dead”. Well, actually it is “Spinning Rust is (almost) Dead”. Why, given all of the facts, do I say “almost“? Disks are really good at one thing: storing a LOT of data. So for backup, archival, or storing many terabytes of data that gets accessed only occasionally, disks are good. Data centers should Continue reading Spinning Rust is (almost) Dead, Part 5, Almost?
“But wait,” you say, “price and performance aren’t everything!” Really? You are correct. Reliability counts when your data is sitting on the drive. To start with, think about microscopic magnetic heads flying back and forth over platters spinning at 7,200 rpm to 15,000 rpm. Need I say more? We can compare manufacturer’s MTBF (Mean Time Between Failure) numbers, but nobody really knows how they Continue reading Spinning Rust is (almost) Dead, Part 4, SSD Power and Reliability
Finally, we get to the question, “What replaces hard disk drives?” As many people already know, the answer is solid state disks or SSDs. SSDs are made today to fit the shape, size and interfaces used by hard disk drives (HDDs), but they consist mostly of Flash memory instead of spinning rust, plus a controller and some RAM for buffering, just like a rotating Continue reading Spinning Rust is (almost) Dead, Part 3, SSD Price vs. Performance
That brings us back to spinning rust. To understand the limitations of rotating hard disk drives, it is important to understand the technology. With a basic grasp of how a disk drive works, the mechanical limitations quickly become obvious. If you are accessing data sequentially in big long chunks, where the disk can read an entire track, move over just one track and read Continue reading Spinning Rust is (almost) Dead, Part 2, Disk Drive Physics
“Spinning rust?” you may say? Yes, rust, or another iron oxide, is the ferromagnetic coating on the platters spinning inside every hard disk drive. To read and write your data an actuator arm, driven by a separate motor moves a tiny recording head over each platter surface, flying on a microscopic layer of air to change the magnetic polarization one bit at a time. Continue reading Spinning Rust is (Almost) Dead, Part 1, The Pace of Technology