Horse Sense #98

The Importance of IOPS

Welcome to 2012!

In this issue of Horse Sense:
-Things we thought you should know
-The Importance of Backup
-The Importance of IOPS

Here are some things we thought you should know:

-On 1/1/2012, HP raised prices on some of its toners 10-17%.  Lexmark also increased supply prices 3-7%.  They say these increases are due to global economic conditions, currency volatility, product supply costs, and transportation costs.

-Following the massive increases and availability issues due to the floods in Thailand, hard drive makers Seagate and Western Digital are lowering the warranties on their drives 1/1/2012. Most Seagate desktop drives will go from a 2 year to a 1 year warranty, and most enterprise drives and some high performance desktop drives will go from a 5 year to a 3 year warranty. Only Western Digital's Blue and Green series desktop drives will drop from 3 to 2 years, while performance and enterprise drives will continue to have a 5 year warranty. Hard drive allocations are expected to continue for at least 6 more months.

-Solid State Drive (SSD) pricing at the end of 2011 reached $1/GB retail pricing for some drives. SSDs have been selling well due to the increases in price and shortages of traditional hard drives.

-At the end of 2010, according to Intel:
247 billion e mails were sent each day and 70-90% of them were spam.
There were 1 million computers sold per day, and the majority of them were portable.
There were 2 billion videos seen on YouTube alone in a day.
There were 2.5 billion photos placed on FaceBook alone in a day.

-Cell phone bandwidth is quite limited when compared to cable or fiber connections to your house. Now that people are downloading books to their electronic readers and, much worse, trying to watch video on their phones and tablets via their cellular connections, there is a real shortage of bandwidth. To combat that, cell phone companies are curtailing unlimited bandwidth plans, deliberately slowing connections after a certain amount of data has been received, charging more for "premium" service, and other tactics to limit the overall impact on their network. A single movie played on a tablet could consume enough bandwidth for hours that other people might not be able to do anything else. If you are old enough, you might remember a similar situation played out with dial up access to the Internet many years ago. Phone companies found themselves short of capacity when systems designed for 2 minute average voice calls were faced with modem users camping on those same lines for 2 hours.

The Importance of Backup (Statistics from Intel)

-It costs $8000 per megabit to regenerate data from scratch.
-It takes 19 man days to reenter 20MB of sales data.
-60% of small businesses suffering a catastrophic data loss are out of business within 6 months.

The Importance of IOPS

You are going to start seeing the term IOPS more often. I have written a number of articles in Horse Sense that discussed latency and why it is so important in computing (in Google, search for "latency site: " to see the most recent ones). IOPS is an abbreviation for Input/Output operations Per Second. IOPS is a measure of how much work you can do during one second and is inversely related to latency. For example, to read 4KB of data may take 1 millisecond, which gives you 1,000 IOPS. Unfortunately, standard magnetic hard disks are not that responsive. They tend to top out at less than 200 IOPS. This is because there is a lot of physical movement involved in reading or writing from a hard disk and that takes time. Lower end Solid State Drives (SSDs) on the other hand, typically exceed 20,000 IOPS. Enterprise SSDs and SSD arrays can hit 2 million IOPS or more ( High end hard disks can transfer data at up to 145MB/s, but a single low end SSD can exceed 550MB/s. In addition, typical SSDs use 2 to 50 times less power, depending on whether you are comparing idle or working drives. SSD equipped devices run without drive noise and often without fan noise because extra air cooling is not needed. An SSD has a shock resistance that is 5 to 50 times better than a standard hard drive. You can hit an SSD with a baseball bat and as long as you don't break any of the connections, it will still function!

But IOPS and SSDs sound esoteric. Why should you care about them? IOPS is a standardized measure of how much work you can do in a given amount of time. If you need to do less than 200 IOPS of work, then it does not matter whether you are using an SSD or a traditional hard drive. Modern multi-core processors are capable of doing much more work, so your storage system can act like a really large rock behind your car. When would you need more than 200 IOPS? It turns out that it happens more often than you think. IOPS becomes critically important any time you are doing work that causes you to perform lots of read or write operations in a fairly random fashion. Reading large directories in Windows, indexing files for search purposes, scanning files for viruses, searching for a particular e mail, compacting e mail folders, working with a database, booting your system, shutting down your system, having your system go into hibernation or resume from hibernation, and other tasks trigger a huge number of reads and/or writes. Even "normal" tasks can be taxing if your disk is fragmented. Reconstructing the pieces of fragmented files requires that the read/write heads of a traditional hard disk reposition lots of times. It looks literally like the arm of a record player moving back and forth across a record. Needless moving of the head across a fragmented hard disk compromises both performance and longevity and is why I recommend disk defragmentation programs. While files on SSDs can become fragmented, the time needed to access the pieces is minimized, so fragmentation issues do not disappear, but they become less of an issue.

Perhaps an even more common case where more IOPS are needed is when a user is multitasking. If you have multiple windows open at the same time doing different things, and if those things require access to the disk, they are competing against one another. Data for those tasks may be scattered all over the disk. Though your multi-core processor may be able to handle multiple tasks at once, if your storage system cannot deal with the requests for information, those extra cores are wasted. In modern computing, the responsiveness of your storage system plays a huge role in how well the system responds as a whole. Where IOPS becomes critically important is on servers, especially those with larger databases. You would naturally expect different users to need different information. So, it is like multiplying the single user multitasking case by each user. On servers, you can run out of IOPS quickly. To combat this problem, database vendors have recommended that high performance databases be spread across a large number of conventional hard disks in a RAID array to provide the needed number of IOPS for the organization. A single SSD can replace multiple hard drives and provide the needed IOPS in this case with far less cost and complexity. A fairly readable article on this can be found here (just ignore the application specific stuff): <>

A lowly desktop user can easily see a difference when using SSDs versus hard disks. Operations involving disk access will happen more quickly. The computer will be more responsive. It will not seem to freeze or think as often because it is waiting for the disk to respond. Tasks will continue smoothly. For example, hard disk backups or copies of directories will often stutter with conventional hard disks as the disk finds something else to back up. This will not happen with SSDs. You can even see this happen on a network by watching how bandwidth is used. An SSD trying to fill that network pipe will do so whereas a hard disk will have a spiky looking graph indicating drops in transfer rates and take longer. Laptops run cooler and longer because SSDs take less power, and adding an SSD to a laptop is especially noticeable as they tend to use hard disks that spin slower and/or stop spinning when unused to save on energy and noise. The effect is so dramatic, that when I bought a new laptop for my wife and son to use this Christmas, they refused to use it until I installed an SSD.

With the rise in hard disk prices and the drop in SSD prices, we should no longer consider them esoteric or for the high end. In fact, with the productivity gains that can be realized by tying SSDs to modern multi-core processors, at least one of your drives in your next PC should be a solid state drive.  In fact, you should seriously consider replacing or augmenting the conventional hard drive in your current PC to speed it up and extend its useful life. And, although caching solutions and hybrid drives do exist and have their place, I submit that only the higher cost per gigabyte of SSDs is keeping everyone from adopting them wholesale. If your storage needs are fairly minimal, and most desktops and laptops do not need a lot of storage, solid state is the way to go. If you need lots of IOPS or high throughput, solid state is the way to go as well. Only if you need massive amounts of inexpensive storage should you really keep looking at traditional hard drives.


©2012 Tony Stirk, Iron Horse