March 2013 – The SSD Guy Blog

Seagate Upgrades Hybrids, Phases Out 7,200RPM HDDs

Seagate made two important statements on two successive days – March 4 and 5: First, the company disclosed plans to phase out its 7,200 RPM 2.5″ notebook HDDs, and second, Seagate announced a new line of Momentus XT hybrid hard drives, which the company calls: “Solid State Hybrid Drives” or “SSHDs.”

Are these two announcements related? Well, The SSD Guy thinks they are!

Higher-RPM HDDs help to accelerate disk accesses by a small percentage while a hybrid can boost speeds significantly. According to Seagate, Continue reading “Seagate Upgrades Hybrids, Phases Out 7,200RPM HDDs”

Are HDDs Vibration Sensitive?

One reason to use SSDs is that, with no moving parts, these devices are insensitive to shock and vibration. HDDs, on the other hand, are sensitive enough to vibration that it can cause access delays.

How sensitive are they? Well, I have seen some overblown claims from SSD makers that shock will cause HDD head crashes. I am not sure that I believe such claims, but I certainly do believe that an HDD’s actuator (the read/write head mechanism) can be shaken away from its track, causing a Continue reading “Are HDDs Vibration Sensitive?”

One-Hop vs. Two-Hop PCIe SSDs

Lately a number of PCIe offerings have hit the SSD market. The SSD Guy breaks them into two camps: One-Hop SSDs, in which the commands are translated directly from PCIe to the NAND flash without going through an intermediary protocol, and Two-Hop SSDs, which use off-the-shelf HBAs and SATA SSD controllers to move commands first from PCIe to SATA then from SATA to NAND. There are aslo versions that go through SAS: PCIe to SAS, then SAS to NAND.

The SSD Guy figured that Easter would be a good time to talk about these since everyone already has the Easter Bunny hopping through their minds!

It’s not hard to understand why Continue reading “One-Hop vs. Two-Hop PCIe SSDs”

Understanding Storage Delays

Jim Pappas of Intel, a fellow member of SNIA (the Storage Networking Industry Association) shared a really intuitive way to understand storage delays at the last Storage Developer Conference (SDC). It’s very simple. First consider these two facts:

The difference between the speed of system memory and that of a hard disk drive (HDD) is roughly 6 orders of magnitude, or 1 million times
SSDs split the gap. An SSD is about 1,000 times faster than an HDD, and is about 1,000 times slower than system memory. Memory access times are measured in nanoseconds (ns), SSDs in microseconds (µs) and HDDs in milliseconds (ms)

The problem with understanding this (ns, µs, ms) is that Continue reading “Understanding Storage Delays”

Nimbus Upgrades both Software and Hardware

Nimbus Data made a dual announcement on Monday, introducing an upgrade to the company’s zero-license-fee Halo storage management software and announcing volume shipments of the new Gemini storage array.

The Halo storage software, which already boasts a rich feature set, has added a new API, a mobile access to performance information, and powerful analytics tools that track and report over 200 metrics in real time with unlimited scroll-back.

The Nimbus Gemini system has already been shipping for a couple of months and is finding acceptance in Continue reading “Nimbus Upgrades both Software and Hardware”

LSI’s Take on Data Center Flash

LSI Corp. has launched a new blog that covers (among other things) flash storage. It’s only natural – the company’s SandForce subsidiary is riding high on the SSD wave and LSI’s HBAs are finding widespread use, both internally and externally, in the production of two-hop PCIe SSDs.

A recent post called “What are the Driving Forces Behind Going Diskless” by LSI Fellow Rob Ober outlines the leading Continue reading “LSI’s Take on Data Center Flash”

Violin Bets on Both Sides

Violin Memory today made some important announcements. The company has introduced a new line of one-hop PCIe SSDs, and Toshiba will be carrying these as its own products. This creates a tighter link between the two companies: Toshiba is already an investor in Violin, and Toshiba Japan already sells Violin’s memory arrays in Japan.

The new PCIe SSDs are based on Violin’s high-performance NAND management technology, and Violin claims that they offer a higher performance/price point that is available from any other PCIe SSD vendor. This is a key point because PCIe SSD performance varies across a very broad range.

But why does The SSD Guy say that Violin’s betting on both sides? Ever since discrete SSDs started to find their way into the data center there has been a heated debate: Do SSDs belong on the server side of the network or as shared storage? In a virtualized configuration all storage is shared to allow a task to easily move from one server to the next. In an HDD-based system this makes a lot of sense, since an HDD’s latency is significantly larger than that of the network. With SSDs that equation changes – the SSD’s latency is significantly lower than that of the network. The network dramatically reduces the performance of the SSD, so it makes more sense to move that part of the storage into the server, but this breaks the “Shared Storage” model.

This post’s graphic comes from a slide that I have shown repeatedly explaining that it’s wrong to take sides in this argument. Eventually solid state storage will find its way into both sides of the network. In the server it serves as an alternative to large DRAMs, and if it is managed as memory and not as storage, then there will never be any data consistency problems. Of course, most caching solutions also help in this regard, allowing server-side flash to be managed as persistent storage. On the other side of the network flash as shared storage also makes a lot of sense since it accelerates access to shared storage, which is the basis for all virtualized systems.

Violin has taken this argument to heart, betting on flash adoption on both sides of the network, and is the first flash storage array start-up to do so. It will now only be a matter of time before others fall in line.

Objective Analysis covers the enterprise SSD market very closely, issuing reports like our well-regarded annual update covering the enterprise SSD market: The Enterprise SSD: Technologies & Markets. We also perform custom consulting in this area. Clients who wish to engage with us are welcome to drop The SSD Guy a line.

SSDs and TCO

One of the best arguments to use an SSD is also one of the most difficult ways to sell anything. This is the Total Cost of Ownership, commonly abbreviated to “TCO.”

TCO has been used as an argument for buying anything from compact fluorescent bulbs to Jaguar automobiles.

The argument usually revolves around an item whose initial price is higher, but which has lower ongoing (or operating) costs, and when these costs are combined, the higher-priced item proves to cost less to own over the long run. In the case of a compact fluorescent (CF) bulb, the bulb may cost $7, versus $1 for an incandescent bulb, but it consumes 18 Watts compared to the 75 Watts consumed by the incandescent bulb it replaces. In addition the CF bulb lasts ten times as long (10,000 hours vs. 1,000 hours.) This works out to a savings of 470 kWh – or about $50 – plus $3 in bulb costs. Continue reading “SSDs and TCO”

‘Noisy Neighbor’ or Cuckoo?

SolidFire has launched a campaign about a phenomenon the company calls the “Noisy Neighbor.” This term is used to express a concept in which one very demanding application absorbs all of the data center’s storage resources to the performance detriment of all other applications. The company points out that this leads to performance variability and poor Quality of Service (QoS.) This, in turn, can drive the enterprise to shun cloud-based services.

The SSD Guy sees this phenomenon as something similar to a “Denial of Service” (DoS) attack, or even the way that cuckoos reproduce. One resource demands more than its fair share of support driving performance below acceptable levels. Heck, even the politics of water rights works this way. In this particular case the constrained resource isn’t network bandwidth, food, or water, but storage bandwidth.

At the bottom of its Noisy Neighbor press release SolidFire has posted an interesting infographic that explains this phenomenon and brings the consequences to monetary terms. Naturally it advocates solid state storage as a solution to the problem. It’s worth a look.