Server Talk Episode 4: Storage Media

In this episode of Server Talk, Alexey and Mike discuss the various forms of storage media and technology available: covering traditional spindle hard drives (HDDs), solid-state technology (SSDs), and Peripheral Component Interconnect Express (PCI-e). This timely episode comes on heels of a major announcement by Hitachi Global Storage Technologies (HGST) for the summer release of their new 12Gb/s SAS SSD family. 12Gb/s SAS is an emerging technology which will have a tremendous impact on the world of enterprise storage.

In this podcast, we take a look a various forms of storage media and the technologies have evolved: from “old-fashioned” spinning disk drives to emerging 12Gb/s SAS products. More importantly, Alexey teaches Mike and our listeners about the relative strengths and weaknesses of each technology, and how to properly select each for a new server.

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 Topics Covered:

  • ICC news –nNew building update
  • Industry news – 12Gb/s SAS
  • Connectivity – SATA and SAS
  • Types of storage media – HDDs, SSDs, PCI-e
    • Benefits and drawbacks of each

After a brief mention of the concepts of “connectivity” and “12Gb/s SAS”, Alexey dives right into discussing the different forms of storage media:

Alexey: There’s pretty much two different types of storage media. We have spinning – spindle disks – and then we have flash based disks. You also mentioned PCI-e, and that is also flash based technology.  So, in spindle disks, it’s a rotating platter where your information gets stored on to and in flash, it’s a RAM. So, it electronically gets stored versus spinning. Obviously these two technologies are very different. They’re used for different areas. Some store a lot more information, some store a lot less. Some are fast, some are slow. In spinning disks, we have things like something called RPM – revolutions per minute. And, that’s how fast the disk spins. The faster it spins the more information it can take so it’s faster response so they can take more information and give you more information back. Whereas flash disks, they don’t even have RPM. Because it’s electronic, they’re a lot faster than spinning disks.

Mike: Gotcha. A real quick question about spinning disks. What are the standard spin rates? 5400 and 7000, or something?

Alexey: No… Well, 5400 is typically what’s used with laptops just to save the power. Servers are typically at 7200 RPM. Some of the faster disks are known as 10k or 15k. And, we’re seeing areas where the industry’s changing a little bit. Before, we have a lot more 15k, people are going away from the 15k more to 10k and focusing a lot more on SSDs when they really need that performance.

Mike: Got you. And then another real quick side note. You mentioned that the faster – the more RPMs – the faster it can read information but does that also apply to writing information?

Alexey: That’s correct.

Mike: So faster RPMs is both better for accessing information and for creating it?

Alexey: Alright, what you actually just described is something that is called IOPS – operations per second. More specifically read/write operation per second.

Mike: Very interesting, very cool. So, I know connectivity plays a really big role when it comes to storage. Let’s get into that a little bit more.

Alexey: So, there are primarily two types of connectivity. Types of connectivity will be SATA and SAS. SATA is Serial Attached ATA. SAS is SCSI Attached Serial / Serial Attached SCSI, I keep on forgetting which one it is. They’re very similar technologies. SAS is the more enterprise version. SATA is the consumer base and also used the servers. SATA – you’re going to find just about everywhere – your laptop, your desktop computer, your server. That’s just the basic technology. That, right now, operates at 6 “gigs a second” (gigabits per second or Gb/s) and what that means is that it can support up to 6 gigs(bits) of data per second. What’s interesting when you mention 12 Gb/s in our news… 12 Gb/s is going to support double the amount of data. Well, a normal hard drive can’t really produce that much data because it physically has to spin and has to access data and so on, so it can’t produce that much data whereas SSDs, since it’s flash and electronic, it can. So, what we’re actually going to see is that SSDs are the first devices that’s going to be 6 Gb/s and I think we’re going to see those roughly… July timeframe. So, what makes it even more interesting is that 12 Gb/s… the technology for 12 Gb/s is only in SAS. So, SATA devices will not support 12 Gb/s. That’s just because that’s the way technology is designed. So, we’re going to see spinning disks and SSDs and 12 Gb/s only on SAS.

Mike. Ok, so would you say that spindle disks are other way out? Like, is there…

Alexey: No. That is a very good question. So, maybe 4 or 5 years ago when SSDs were introduced, everyone was saying “Hey, spinning disks are going to disappear” and here we are today – sometime later – and they’re still around. Reason for this is, to produce the flash in SSDs it’s a lot more expensive. So, you have smaller sizes, smaller capacities, but they’re very, very fast. Where hard drives are spinning disks, they’re not as fast but they support large capacities. So, depending on what you’re doing, workload-wise, it’s going to depend on if you just use SSDs or spinning disks or a combination between the two.

Alexey makes an important point, something that is a recurring theme throughout our podcasts: the technology you choose is very specific to your application and purpose. That’s a big point to understand in enterprise technology. Solutions are often designed to fill specific needs.

Mike: I got you. So, if your primary objective is to store as much data as possible, you’re basically going to be using spindle disks. And if you need very fast connectivity, you’re going to be using SSDs.

Alexey: Not connectivity – if you’re going to need really fast access. If you just need very, very fast drive. So, you’re making it black-and-white but there’s nothing black-and-white in the industry. It’s all grey. So, a lot of the systems we’re seeing nowadays is a mixture. So, you have your spinning disks for long-term storage and for data that you’re not accessing a lot; whereas, “hot data” – or data that you’re accessing a lot – is more in solid state or SSDs. So, another benefit of spindle disks is streaming data. SSDs operate very, very well in terms of small files… in converting a lot of small files, reading a lot of small files that’s where SSDs excel but large files, you don’t get any benefits. So, hard drives still, are better for larger files.

Mike: I got you. So, what that implies is that SSDs are really good at switching tasks?

Alexey: That’s correct.

Mike: That they’re really good at… the time in between… the time that it would take to switch from one operation to another is shortened but the actual operation’s itself is the same?

Alexey: To give you an industry number, a spinning disk – depending on how fast it spins – 7200 RPM drive will spin roughly at about 80 IOPS… Not spin – will produce 80 IOPS. 10,15k drive can produce roughly up to 200 items – roughly. In SSDs, just about any SSDs is going to be around 50,000 IOPS.  So, you have a really, really big difference between SSDs and hard drives in terms of IOPS. And again, those SSDs are going to perform really well in switching tests, accessing all the small files… It’s all electronic, it’s not spinning, it does it quickly but if it’s a lot of large data, there’s no benefit of it. So, that’s what we can expect.

Mike: Got you. So, how much do you think SSDs have penetrated the market at this point? I ask questions like these in every podcast. Do most of your customers get some sort of combination or would you say that it’s weighted in more terms than the other – 20% towards SSDs, 80% one way? You know, what will be the distribution between one way, between spindle, some combination and SSDs?

Alexey: To answer that question, it really depends on what the customer is doing. So, what kind of system are they purchasing?  If they’re purchasing a purely storage system, they’re going to do hard drives. They might have a few SSDs in there just to boost their performance it’s going to be mostly hard drives. If they’re going to be looking for pure performance, it’s going to be SSDs but as mentioned, the environment’s not always like that so we are going to get a lot in the middle. To give you an example, I’ll probably say it’s broken down to 40% hard drives, 40% mixture and maybe 20% just straight up SSDs.  Maybe a little bit more on the SSD side, but it’s kind of hard to say.

Mike: Ok. Alright, that’s roughly what I was asking for. I was about to accuse you of avoiding the question.

Alexey: Don’t worry. So, where we’re also with SSDs is that in operating systems, a lot of times, it’s basically required just to host an operating system. You don’t need a lot of space, so some people just go for SSDs. It’s cheaper for local capacities – it’s fast, cheap and it lasts forever. That’s actually one of the things we should talk about. Spinning disks, they spin. It’s a physically moving part. So at some point, it’s going to stop spinning. Where SSDs, it’s electronic. As long as it has some current, it’s going to operate.

Mike: Okay. So, SSDs are more dependable?

Alexey: That’s correct. They can withstand temperatures a lot better; they’re a lot more dependable. They still have a threshold of how much IOPS you can do on them and how many read and writes you can put on them but they’re significantly more dependable than spindle.

Mike: Got you. And then, I’m sure since it’s a physical disc there’s a chance of the disc all being warped… based on humidity, and whatnot?

Alexey: Yup, just physical failure.

Mike: Ok, I got you. Alright, so how does form factor play into all this? I imagine that you’d have a different box depending on… you know…

Alexey: Box is a very specific term. So, you have to store all these information, all these drives somewhere. So there are two types of form factors for most drives. There’s something known as 3.5 inch and 2.5 inch. 2.5 inch is a smaller form factor versus 3.5 inch. Most SSDs are going to be 2.5. A lot of the higher spindle disks are also going to be 2.5”.  The larger capacity disks are going to be 3.5”. So, the chassis that you’re installing these drives in have to support the 3.5”, the 2.5” and the quantity that you want to support. So, say for example, you want a lot of storage space and you want to install 30 drives, 30 spinning disks to get… if we’re talking about 3 terabyte a disk, 90 terabytes of space, well, you need 30 base. It’s a lot of room, physical room that you need a data center in your office to install all those drives versus a smaller disc or if you’re just looking for performance, you don’t need to go with a large disc. You can go with a small disc; you don’t need as much physical room.

Mike: I got you. So these are very serious considerations for data centers and whatnot?

Alexey: Yeah, well the more drives you have, the more power consumptions you have, the more you need it to cool. SSDs actually consume less power and you don’t need it to cool as much as drives. What we actually saw, I want to say 10-15 years ago: you install 10-15 spinning disks, because they were so close to each other they start overheating. A lot of times, the vibration from fans would kill them because they’re spinning so you would see a lot of different problems with them. Nowadays, that’s all fixed but SSDs completely eliminated all those issues.

Mike: Got you.

Alexey; There’s one other form factor that we kind of mentioned – the PCI-e. PCI-e is actually a card – a physical card that gets installed onto the motherboard. So, it’s not even a drive, well, it’s not a hard drive or not a typical hard drive that’s a 3.5” or 2.5” form factor. It gets its own slot on the motherboard. And what it does is it’s much faster. So it still uses flash like an SSD but it goes directly into the motherboard which lowers the latency, the amount of time that you got to talk between all the different components to get from the motherboard to the SSD it eliminates all those directly into the PCI-e card. So, lower latency, those are typical in financial applications or applications that need very, very, very quick response time.

Mike: So, what are the disadvantages of PCI-e?

Alexey: The pricing.

Mike: Is that it?

Alexey: Primarily, yes.

Mike: So, it’s just an expensive technology?

Alexey: Yeah, you’re actually bringing up a very interesting point. It’s a little early to talk about this technology but I want to say maybe, we’re, probably a year out or maybe even more, we’re going to see PCI-e technology take over SAS and SATA. So, we’re going to start seeing PCI-e drives. And, I don’t know too much about this technology, it’s just there’s development out there and I have very limited information about it, but the drives are going to have these universal connectors that the system itself will detect if it’s PCI-e, SATA, or if it’s SAS and it will auto-negotiate everything and figure it out by itself. But the form factor’s probably going to be 2.5” for that new PCI-e technology.

Mike: Right, and that’s advantageous because it saves a lot of space.

Alexey: Right.

Mike: Very cool. Alright then, anything else you’d like to discuss in storage media?

Alexey: That, I think primarily covers everything. It paints an overall picture. There’s obviously a lot more details than we can go into. It really just depends on what the end-user is doing with the system. So, a lot of these decisions are really made just by what they’re doing: what kind of performance are they looking for, how much space they have, how much cooling they have… performance is going to probably be the bigger question and the capacity. I think that kind of sums everything up.

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