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Save the planet – buy fatter disks and flash

Posted on April 22, 2010April 10, 2012 by Ray in Storage, Storage density, Storage energy use

Hard drive capacity overt time (from commons.wikimedia.org) (cc) — PC hard drive capacity over time (from commons.wikimedia.org) (cc)

Well maybe that overstates the case but there is no denying that both fatter (higher capacity) drives and flash memory (used as cache or in SSDs) saves energy in today’s data center. The interesting thing is that the trend to higher capacity drives has been going on for decades now (see chart) but only within the last few years has been given any credit for energy reduction. In contrast, flash in SSDs and cache is a relative newcomer but saves energy nonetheless.

I almost can’t recall when disk drives weren’t doubling in capacity every 18 to 24 months. The above chart only shows PC drives capacities over time but enterprise drives have followed a similar curve. The coming hard drive capacity wall may slow things down in the future but just last week IBM announced they were moving from a 300GB to a 600GB 15Krpm enterprise class disk drive in their DS8700 subsystem. While doubling capacity may not quite halve energy use, it’s still significant. Such energy reductions are even more dramatic with slower, higher density disks. These SATA disks are moving from 1TB to 2TB later this year and should cut energy use considerably.

Similarly, NAND flash density used in SSDs is increasing capacity at almost a faster rate than disk storage. ASIC feature size continues to shrink and as such, more and more flash storage is packed onto the same die size. Improvements like these are doubling the capacity of SSDs and flash memory. While SSD power reduction due to density improvements may not be as significant as disk, we hope to see a flattening out of power use per NAND cell over time. This flattening out of power use is now happening with processing chips and we see little reason why similar techniques couldn’t apply to NAND.

But the story with flash/SSDs is a bit more complicated:

SSDs don’t consume as much energy as a standard disk drive at the same capacity, so a 146GB enterprise class SSD should consume much less energy than a 146GB enterprise class disk drive.
SSDs don’t exhibit the significant energy spike that hard disk drives encounter when driven at higher IOPs and was discussed in SSDs vs. Drives energy use.
SSDs can often replace many more disk spindles than pure capacity equivalence would dictate. Some data centers use more disks than necessary to spread workload performance over more spindles wasting storage, power and cooling. Moving this data to SSDs or adding flash cache to a subsystem, spindle counts can be reduced dramatically and as such, slash energy use for storage.

All this says that using SSDs or flash in place of disk drives reduces data center power requirements. So if you’re interested in saving energy and thus, helping to save the planet, buy fat(ter) disks and flash for your data storage needs.

Brought to you on behalf of Planet Earth in honor of Earth Day.

Is M and A the only way to grow?

Posted on January 20, 2010 by Ray in Corporate growth, Strategy, Visionary leadershp

Photograph of Women Working at a Bell System Telephone Switchboard by US National Archives (cc) (from flickr)

Oracle buys Sun, EMC buys Data Domain, Cisco buys Tandberg, it seems like every month another major billion dollar acquisition occurs. Part of this is because of the recent economic troubles, which now values many companies at the lowest they have been for many years and thus, making it cheaper to acquire good (and/or failing) companies. But one has to wonder is this the only way to grow?

I don’t think so.

Corporate growth can be purely internally driven or organic just as well as from acquisition. But it’s definitely harder to do internally. Why?

Companies are focused on current revenue producing products – Revolutionary products rarely make it into development in today’s corporations because they take resources away from other (revenue producing) products.
Companies are focused on their current customer base – Products that serve other customers rarely make out into the market from today’s corporations because such markets are foreign to the companies current marketing channels.
Company personnel understand current customer problems – To be successful, any new product must address it’s customer pain points and offer some sort of a unique, differentiated solution to those issues and because this takes understanding other customer problems, it seldom happens.
New products can sometimes threaten old product revenue streams – It’s a rare new product that doesn’t take market share aware from some old way of doing business. As companies focus on a particular market, any new product development will no doubt focus on those customers as well. Thus, many new internally developed products will often displace (or eat away at) current product revenue. Early on, it’s hard to see how any such product can be justified with respect to current corporate revenue.
New products often take efforts above and beyond current product activities – To develop, market and sell revolutionary products takes enormous, “all-out” efforts to get off the ground. Most corporations are unable to sustain this level of effort for long, as their startup phase was long ago and long forgotten.

We now know how hard it can be but how does Apple do it? The iPod and iPhone were revolutionary products (at least from Apple’s perspective) and yet they both undeniably became great successes and helped to redefine industries in the process. And no one can argue that they haven’t helped Apple to grow significantly in the process. So how can this be done?

It takes strong visionary leadership in the company at the highest level – Such management can make the tough decisions to take resources away from current, revenue producting products and devote time and effort to new ones.
It takes marketing genius – Going after new markets, even if they are adjacent, requires in-depth understanding of new market dynamics and total engagement to be succesful.
It takes development genius – Developing entirely new products, even if based on current technology, takes development expertise above and beyond evolutionary product enhancement.
It takes hard work and a dedicated team – Getting new products off the ground takes a level of effort above and beyond current ongoing product activities.
It takes a willingness to fail – Most new internally developed products and/or startups fail. This fact can be hard to live with and makes justifying future products even harder.

In general, all these items are easier to find in startups rather than an ongoing corporation today. This is why most companies today find it easier and more successful to grow through acquisitions rather than through organic or internal development.

However, it’s not the only way. ATT did it for almost a century in the telecom industry but they owned a monopoly. IBM and HP did it occasionally over the past 60 years or so, but they had strong visionary leadership for much of that time and stumbled miserably, when such leadership was lacking. Apple has done it over the past couple of decades or so but this is mainly due to Steve Jobs. There are others of course, but I would venture to say all had strong leadership at the helm.

But these are the exceptions. Strong visionary leaders usually don’t make it to the top of today’s corporations. Why that’s the case needs to be the subject of a future post…

Latest SPC-2 results – chart of the month

Posted on December 22, 2009October 8, 2012 by Ray in MPBS, SPC-2, Storage, Storage performance, Storage Performance Council, VOD

SPC-2* benchmark results, spider chart for LFP, LDQ and VOD throughput

Latest SPC-2 (Storage Performance Council-2) benchmark resultschart displaying the top ten in aggregate MBPS(TM) broken down into Large File Processing (LFP), Large Database Query (LDQ) and Video On Demand (VOD) throughput results. One problem with this chart is that it really only shows 4 subsystems: HDS and their OEM partner HP; IBM DS5300 and Sun 6780 w/8GFC at RAID 5&6 appear to be the same OEMed subsystem; IBM DS5300 and Sun 6780 w/ 4GFC at RAID 5&6 also appear to be the same OEMed subsystem; and IBM SVC4.2 (with IBM 4700’s behind it).

What’s interesting about this chart is what’s going on at the top end. Both the HDS (#1&2) and IBM SVC (#3) seem to have found some secret sauce for performing better on the LDQ workload or conversely some dumbing down of the other two workloads (LFP and VOD). According to the SPC-2 specification

LDQ is a workload consisting of 1024KiB and 64KiB transfers whereas the LFP consists of 1024KiB and 256KiB transfers and the VOD consists of only 256KiB, so transfer size doesn’t tell the whole story.
LDQ seems to have a lower write proportion (1%) while attempting to look like joining two tables into one, or scanning data warehouse to create output whereas, LFP processing has a read rate of 50% (R:W of 1:1) while executing a write-only phase, read-write phase and a read-only phase, and apparently VOD has a 100% read only workload mimicking streaming video.
50% of the LDQ workload uses 4 I/Os outstanding and the remainder 1 I/O outstanding. The LFP uses only 1 I/O outstanding and VOD uses only 8 I/Os outstanding.

These seem to be the major differences between the three workloads. I would have to say that some sort of caching sophistication is evident in the HDS and SVC systems that is less present in the remaining systems. And I was hoping to provide some sort of guidance as to what that sophistication looked like but

I was going to say they must have a better sequential detection algorithm but the VOD, LDQ and LFP workloads have 100%, 99% and 50% read ratios respectively and sequential detection should perform better with VOD and LDQ than LFP. So thats not all of it.
Next I was going to say it had something to do with I/O outstanding counts. But VOD has 8 I/Os outstanding and the LFP only has 1, so the if this were true VOD should perform better than LFP. While LDQ having two sets of phases with 1 and 4 I/Os outstanding should have results somewhere in between these two. So thats not all of it.
Next I was going to say stream (or file) size is an important differentiator but “Segment Stream Size” for all workloads is 0.5GiB. So that doesn’t help.

So now I am a complete loss as to understand why the LDQ workloads are so much better than the LFP and VOD workload throughputs for HDS and SVC.

I can only conclude that the little write activity (1%) thrown into the LDQ mix is enough to give the backend storage a breather and allow the subsystem to respond better to the other (99%) read activity. Why this would be so much better for the top performers than the remaining results is not entirely evident. But I would add that, being able to handle lots of writes or lots of reads is relatively straight forward, but handling a un-ballanced mixture is harder to do well.

To validate this conjecture would take some effort. I thought it would be easy to understand what’s happening but as with most performance conundrums the deeper you look the more confounding the results often seem to be.

The full report on the latest SPC results will be up on my website later this year but if you want to get this information earlier and receive your own copy of our newsletter – email me at SubscribeNews@SilvertonConsulting.com?Subject=Subscribe_to_Newsletter.

I will be taking the rest of the week off so Happy Holidays to all my readers and a special thanks to all my commenters. See you next week.

We need a data storage museum

Posted on December 2, 2009 by Ray in Storage

Core memory, Credit MIT archives, as displayed at the Museum of Computer History

Just returned from Washington DC in the States. It has been decades since I had last seen the Smithsonian American History Museum and I was very saddened to see that their display of information technology of the 40s and 50s had been removed.

It’s unclear to me whether we have a museum of storage anyplace but I think we need one. For starters, technology is changing so rapidly that to see what we had even a few generations ago would take effort.

Why would someone want to see what was done 10 or even 50 years ago in storage. I can think of many reasons:

Innovate on prior technology – Innovation often takes a step backward before it can move forward. By displaying technology that existed 10, 20 to 40 years ago and explaining what it was made of, how it worked, and what it could do for industry someone might be able to innovate on these concepts into an entirely new storage direction.
Visibility of previous technology – The technology of miniaturization has left much of what’s interesting today almost impossible to see and touch. Yesterday’s technology was much easier to see, touch and almost walk through. As such, it was much easier to understand. Educating tomorrows engineers often starts with understanding yesterday technology.
Understand product lifecycles – Products go through a sometimes protracted technological evolution. Lifecycle changes can be supportive as well as destructive of product success. As such, showing how some products changed from generation to generation may help future engineers evolve better products.
Retrieve/recreate old artifacts – Recently, NASA had to retrieve old video feeds from their moon missions and had to revive some old technology to do this. Having a museum chartered with maintaining and displaying old storage technology might have made this job easier. And as more and more of the world’s information is retained as data, this problem only gets worse.
Diversify today’s technology foundations – storage technology has advanced so fast because of it’s singular dependance on electronic semiconductors to shrink and scale. Older technology was much more diverse using mechanics, magnetics, and electronics and as such, not so dependent on one technology. By having a place where the older technology could be researched, whole new breakthroughs, not dependant on today’s semiconductors could emerge that could take storage in totally different directions.

Probably many more reasons why a museum of storage would make sense but these will suffice. I have seen IBM, EMC and other companies product and technology historical displays, but they are not open to the public and there is no central repository for the storage industry as a whole. The problem with corporate displays of technology is that it only represents one view of technological evolution – the survivor’s view. Technological history must include more than just the victors, it must include the life and evolution of the defeated as well.

A storage museum could become a repository for any and every company’s storage technology. Today, for most companies, such technology is often scrapped or at best stored in a basement someplace. Such technology could be brought to light, researched and placed into perspective at a museum of storage.

I think we need such a museum before we lose the technology of the early years of data processing and fear that much of that technology is already gone, more disappearing every day. Also, the history of storage is written mainly in hardware evolution and as such, is easily displayed. As more of storage evolution is implemented via software functionality, it becomes less tangible and thus more easily discardable. If we start with storage hardware, maybe somebody will begin to appreciate the value in recording storage software history as well.

The American Smithsonian has a charter to study the history of technology. Some of this has been on display in Washington and perhaps, at the Museum of Computer History in Mountain View. But nowhere is there a focus on data storage and I believe there should be. How such a museum would be funded, where it would be situated, and how it could be started must be subjects of future posts. Comments?

ESRP results over 5K mbox-chart of the month

Posted on November 24, 2009October 8, 2012 by Ray in Block Storage, ESRP, ESRPv2/Exchange 2007, Storage, Storage performance

ESRP Results, over 5K mailboxr, normalized (per 5Kmbx) read and write DB transfers as of 30 October 2009 — ESRP Results, over 5K mailbox, normalized (per 5Kmbx) read and write DB transfers as of 30 October 2009

In our quarterly study on Exchange Solution Reviewed Program (ESRP) results we show a number of charts to get a good picture of storage subsystem performance under Exchange workloads. The two that are of interest to most data centers are both the normalized and un-normalized database transfer (DB xfer) charts. The problem with un-normalized DB xfer charts is that the subsystem supporting the largest mailbox count normally shows up best, and the rest of the results are highly correlated to mailbox count. In contrast, the normalized view of DB xfers tends to discount high mailbox counts and shows a more even handed view of performance.

We show above a normalized view of ESRP results for the category that were available last month. A couple of caveats are warranted here:

Normalized results don’t necessarily scale – results shown in the chart range from 5,400 mailboxes (#1) to 100,000 mailboxes (#6). While normalization should allow one to see what a storage subsystem could do for any mailbox count. It is highly unlikely that one would configure the HDS AMS2100 to support 100,000 mailboxes and it is equally unlikely that one would configure the HDS USP-V to support 5,400 mailboxes.
The higher count mailbox results tend to cluster when normalized – With over 20,000 mailboxes, one can no longer just use one big Exchange server and given the multiple servers driving the single storage subsystem, results tend to shrink when normalized. So one should probably compare like mailbox counts rather than just depend on normalization to iron out the mailbox count differences.

There are a number of storage vendors in this Top 10. There are no standouts here, the midrange systems from HDS, HP, and IBM seem to hold down the top 5 and the high end subsystems from EMC, HDS, and 3PAR seem to own the bottom 5 slots.

However, Pillar is fairly unusual in that their 8.5Kmbx result came in at #4 and their 12.8Kmbx result came in at #8. In contrast, the un-normalized results for this chart appear exactly the same. Which brings up yet another caveat, when running two benchmarks with the same system, normalization may show a difference where none exists.

The full report on the latest ESRP results will be up on our website later this month but if you want to get this information earlier and receive your own copy of our newsletter – just subscribe by emailing us.

Repositioning of tape

Posted on October 30, 2009 by Ray in Data security, Storage, Storage Backup, Storage density, Storage performance, Storage reliability, Systems

In my past life, I worked for a dominant tape vendor. Over the years, we had heard a number of times that tape was dead. But it never happened. BTW, it’s also not happening today.

Just a couple of weeks ago, I was at SNW and vendor friend of mine asked if I knew anyone with tape library expertise because they were bidding on more and more tape archive opportunities. Tape seems alive and kicking for what I can see.

However, the fact is that tape use is being repositioned. Tape is no longer the direct target for backups that it once was. Most backup packages nowadays backup to disk and then later, if at all, migrate this data to tape (D2D2T). Tape is being relegated to a third tier of storage, a long-term archive and/or a long term backup repository.

The economics of tape are not hard to understand. You pay for robotics, media and drives. Tape, just like any removable media requires no additional power once it’s removed from the transport/drive used to write it. Removable media can be transported to an offsite repository or accross the continent. There it can await recall with nary an ounce (volt) of power consumed.

Problems with tape

So what’s wrong with tape, why aren’t more shops using it. Let me count the problems

Tape, without robotics, requires manual intervention
Tape, because of its transportability, can be lost or stolen, leading to data security breaches
Tape processing, in general, is more error prone than disk. Tape can have media and drive errors which cause data transfer operations to fail
Tape is accessed sequentially, it cannot be randomly accessed (quickly) and only one stream of data can be accepted per drive
Much of a tape volume is wasted, never written space
Tape technology doesn’t stay around forever, eventually causing data obsolescence
Tape media doesn’t last forever, causing media loss and potentially data loss

Likely some other issues with tape missed here, but these seem the major ones from my perspective.

It’s no surprise that most of these problems are addressed or mitigated in one form or another by the major tape vendors, software suppliers and others interested in continuing tape technology.

Robotics can answer the manual intervention, if you can afford it. Tape encryption deals effectively with stolen tapes, but requires key management somewhere. Many applications exist today to help predict when media will go bad or transports need servicing. Tape data, is and always will be, accessed sequentially, but then so is lot’s of other data in today’s IT shops. Tape transports are most definitely single threaded but sophisticated applications can intersperse multiple streams of data onto that single tape. Tape volume stacking is old technology, not necessarily easy to deploy outside of some sort of VTL front-end, but is available. Drive and media technology obsolescence will never go away, but this indicates a healthy tape market place.

Future of tape

Say what you will about Ultrium or the Linear Tape-Open (LTO) technology, made up of HP, IBM, and Quantum research partners, but it has solidified/consolidated the mid-range tape technology. Is it as advanced as it could be, or pushing to open new markets – probably not. But they are advancing tape technology providing higher capacity, higher performance and more functionality over recent generations. And they have not stopped, Ultrium’s roadmap shows LTO-6 right after LTO-5 and delivery of LTO-5 at 1.6TB uncompressed capacity tape, is right around the corner.

Also IBM and Sun continue to advance their own proprietary tape technology. Yes, some groups have moved away from their own tape formats but that’s alright and reflects the repositioning that’s happening in the tape marketplace.

As for the future, I was at an IEEE magnetics meeting a couple of years back and the leader said that tape technology was always a decade behind disk technology. So the disk recording heads/media in use today will likely see some application to tape technology in about 10 years. As such, as long as disk technology advances, tape will come out with similar capabilities sometime later.

Still, it’s somewhat surprising that tape is able to provide so much volumetric density with decade old disk technology, but that’s the way tape works. Packing a ribbon of media around a hub, can provide a lot more volumetric storage density than a platter of media using similar recording technology.

In the end, tape has a future to exploit if vendors continue to push its technology. As a long term archive storage, it’s hard to beat its economics. As a backup target it may be less viable. Nonetheless, it still has a significant install base which turns over very slowly, given the sunk costs in media, drives and robotics.

Full disclosure: I have no active contracts with LTO or any of the other tape groups mentioned in this post.

Chart of the month: SPC-1 LRT performance results

Posted on September 17, 2009October 8, 2012 by Ray in Data security, LRT, SPC-1, Storage, Storage Features, Storage performance, Storage Performance Council, Systems

Chart of the Month: SPC-1 LRT(tm) performance results The above chart shows the top 12 LRT(tm) (least response time) results for Storage Performance Council’s SPC-1 benchmark. The vertical axis is the LRT in milliseconds (msec.) for the top benchmark runs. As can be seen the two subsystems from TMS (RamSan400 and RamSan320) dominate this category with LRTs significantly less than 2.5msec. IBM DS8300 and it’s turbo cousin come in next followed by a slew of others.

The 1msec. barrier

Aside from the blistering LRT from the TMS systems one significant item in the chart above is that the two IBM DS8300 systems crack the <1msec. barrier using rotating media. Didn’t think I would ever see the day, of course this happened 3 or more years ago. Still it’s kind of interesting that there haven’t been more vendors with subsystems that can achieve this.

LRT is probably most useful for high cache hit workloads. For these workloads the data comes directly out of cache and the only thing between a server and it’s data is subsystem IO overhead, measured here as LRT.

Encryption cheap and fast?

The other interesting tidbit from the chart is that the DS5300 with full drive encryption (FDE), (drives which I believe come from Seagate) cracks into the top 12 at 1.8msec exactly equivalent with the IBM DS5300 without FDE. Now FDE from Seagate is a hardware drive encryption capability and might not be measurable at a subsystem level. Nonetheless, it shows that having data security need not reduce performance.

What is not shown in the above chart is that adding FDE to the base subsystem only cost an additional US$10K (base DS5300 listed at US$722K and FDE version at US$732K). Seems like a small price to pay for data security which in this case is simply turn it on, generate keys, and forget it.

FDE is a hard drive feature where the drive itself encrypts all data written and decrypts all data read to from a drive and requires a subsystem supplied drive key at power on/reset. In this way the data is never in plaintext on the drive itself. If the drive were taken out of the subsystem and attached to a drive tester all one would see is ciphertext. Similar capabilities have been available in enterprise and SMB tape drives is the past but to my knowledge the IBM DS5300 FDE is the first disk storage benchmark with drive encryption.

I believe the key manager for the DS5300 FDE is integrated within the subsystem. Most shops would need a separate, standalone key manager for more extensive data security. I believe the DS5300 can also interface with an standalone (IBM) key manager. In any event, it’s still an easy and simple step towards increased data security for a data center.

The full report on the latest SPC results will be up on my website later this week but if you want to get this information earlier and receive your own copy of our newsletter – email me at SubscribeNews@SilvertonConsulting.com?Subject=Subscribe_to_Newsletter.

SSD vs Drive energy use

Posted on August 27, 2009April 12, 2012 by Ray in Storage, Storage energy use, Storage performance

Recently, the Storage Performance Council (SPC) has introduced a new benchmark series, the SPC-1C/E, which provides detailed energy usage for storage subsystems. So far there have been only two published submissions in this category but we look forward to seeing more in the future. The two submissions are for an IBM SSD and a Seagate Savvio (10Krpm) SAS attached storage subsystems.

My only issue with the SPC-1C/E reports is that they focus on a value of nominal energy consumption rather than reporting peak and idle energy usage. I understand that this is probably closer to what an actual data center would see as energy cost but it buries some intrinsic energy use profile differences.

SSD vs Drive power profile differences

The deltas for reported energy consumption for the two current SPC-1C/E submissions show a ~9.6% difference in peak versus nominal energy use for rotating media storage. Similar results for the SSD storage show a difference of ~1.7%. Taking these results for peak versus idle periods, shows the difference for rotating media being 28.5% and for SSD, ~2.8%.

So, the upside for SSD is drive them as hard as you want and it will cost you only a little bit more energy. In contrast, the downside is leave them idle and it will cost almost as much as if you were driving them at peak IO rates.

Rotating media storage seems to have a much more responsive power profile. Drive them hard and it will consume more power, leave them idle and it consumes less power.

Data center view of storage power

Now these differences might not seem significant but given the amount of storage in most shops they could represent significant cost differentials. Although SSD storage consumes less power, it’s energy use profile is significantly flatter than rotating media and will always consume that level of power (when powered on). On the other hand, rotating media consumes more power on average but it’s power profile is more slanted than SSDs and at peak workload consumes much more power than when idle.

Usualy, it’s unwise to generalize from two results. However, everything I know says that these differences in their respective power profiles should persist across other storage subsystem results. As more results are submitted it should be easy to verify whether I am right.