Part 1 of the good post from Greg Schulz (thank you)
Robin Harris (aka @storagemojo) recently in a blog post asks a question and thinks solid state devices(SSDs) using SAS or SATA interface in traditional hard disk drive (HDD) form factors are a bad idea in storage arrays (e.g. storage systems or appliances). My opinion is that as with many things about storing, processing or moving binary digital data (e.g. 1s and 0s) the answer is not always clear. That is there may not be a right or wrong answer instead it depends on the situation, use or perhaps abuse scenario. For some applications or vendors, adding SSD packaged in HDD form factors to existing storage systems, arrays and appliances makes perfect sense, likewise for others it does not, thus it depends (more on that in a bit). While we are talking about SSD, Ed Haletky (aka @texiwill) recently asked a related question of Fix the App or Add Hardware, which could easily be morphed into a discussion of Fix the SSD, or Add Hardware. Hmmm, maybe a future post idea exists there.
Lets take a step back for a moment and look at the bigger picture of what prompts the question of what type of SSD to use where and when along as well as why various vendors want you to look at things a particular way. There are many options for using SSD that is packaged in various ways to meet diverse needs including here and here (see figure 1).
Figure 1: Various packaging and deployment options for SSD
The growing number of startup and established vendors with SSD enabled storage solutions vying to win your hearts, minds and budget is looking like the annual NCAA basketball tournament (aka March Madness and march metrics here and here). Some of vendors have or are adding SSD with SAS or SATA interfaces that plug into existing enclosures (drive slots). These SSDs have the same form factor of a 2.5 inch small form factor (SFF) or 3.5 inch HDDs with a SAS or SATA interface for physical and connectivity interoperability. Other vendors have added PCIe based SSD cards to their storage systems or appliances as a cache (read or read and write) or a target device similar to how these cards are installed in servers.
Simply adding SSD either in a drive form factor or as a PCIe card to a storage system or appliance is only part of a solution. Sure, the hardware should be faster than a traditional spinning HDD based solution. However, what differentiates the various approaches and solutions is what is done with the storage systems or appliances software (aka operating system, storage applications, management, firmware or micro code).
So are SSD based storage systems, arrays and appliances a bad idea?
If you are a startup or established vendor able to start from scratch with a clean sheet design not having to worry about interoperability and customer investment protection (technology, people skills, software tools, etc), then you would want to do something different. For example, leverage off the shelf components such as a PCIe flash SSD card in an industry standard server combined with your software for a solution. You could also use extra DRAM memory in those servers combined with PCIe flash SSD cards perhaps even with embedded HDDs for a backing or preservation medium.
Read on here