Last year, I started my post[Hu Yoshida should know better
I am still wiping the coffee off my computer screen, inadvertently sprayed when I took a sip while reading HDS' uber-blogger Hu Yoshida's post on storage virtualization and vendor lock-in.
HDS is a major vendor for disk storage virtualization, and Hu Yoshida has been around for a while, so I felt it was fair to disagree with some of the generalizations he made to set the record straight. He's been more careful ever since.
However, his latest post [The Greening of IT: Oxymoron or Journey to a New Reality] mentions an expert panel at SNW that includedMark O’Gara Vice President of Infrastructure Management at Highmark. I was not at the SNW conference last week in Orlando, so I will just give the excerpt from Hu's account of what happened:
"Later I had the opportunity to have lunch with Mark O’Gara. Mark is a West Point graduate so he takes a very disciplined approach to addressing the greening of IT. He emphasized the need for measurements and setting targets. When he started out he did an analysis of power consumption based on vendor specifications and came up with a number of 513 KW for his data center infrastructure....
The physical measurements showed that the biggest consumers of power were in order: Business Intelligence Servers, SAN Storage, Robotic tape Library, and Virtual tape servers....
Another surprise may be that tape libraries are such large consumers of power. Since tape is not spinning most of the time they should consume much less power than spinning disk - right? Apparently not if they are sitting in a robotic tape library with a lot of mechanical moving parts and tape drives that have to accelerate and decelerate at tremendous speeds. A Virtual Tape Library with de-duplication factor of 25:1 and large capacity disks may draw significantly less power than a robotic tape library for a given amount of capacity.
Obviously, I know better than to sip coffee whenever reading Hu's blog. I am down here in South America this week, the coffee is very hot and very delicious, so I am glad I didn't waste any on my laptop screen this time, especially reading that last sentence!
Last month, in my post [Disk only customers going back to tape], I mentioned some statistics from the Clipper Group's whitepaper[Disk and Tape Square Off Again —Tape Remains King of the Hill with LTO-4] by analysts David Reine and Mike Kahn.
In that report, a 5-year comparison found that a repository based on SATA disk was 23 times more expensive overall, and consumed 290 times more energy, than a tape library based on LTO-4 tape technology. The analysts even considered a disk-based Virtual Tape Library (VTL). Focusing just on backups, at a 20:1 deduplication ratio, the VTL solution was still 5 times per expensive than the tape library. If you use the 25:1 ratio that Hu Yoshida mentions in his post above, that would still be 4 times more than a tape library.
I am not disputing Mark O'Gara's disciplined approach.
It is possible that Highmark is using a poorly written backup program, taking full backups every day, to an older non-IBM tape library, in a manner that causes no end of activity to the poor tape robotics inside. But rather than changing over to a VTL, perhaps Mark might be better off investigating the use of IBM Tivoli Storage Manager, using progressive backup techniques, appropriate policies, parameters and settings, to a more energy-efficient IBM tape library.In well tuned backup workloads, the robotics are not very busy. The robot mounts the tape, and then the backup runs for a long time filling up that tape, all the meanwhile the robot is idle waiting for another request.
(Update: My apologies to Mark and his colleagues at Highmark. The above paragraph implied that Mark was using badproducts or configured them incorrectly, and was inappropriate. Mark, my full apology [here])
If you do decide to go with a Virtual Tape Library, for reasons other than energy consumption, doesn't it make sense to buy it from a vendor that understands tape systems, rather than buying it from one that focuses on disk systems? Tape system vendors like IBM, HP or Sun understand tape workloads as well as related backup and archive software, and can provide better guidance and recommendations based on years of experience. Asking advice abouttape systems, including Virtual Tape Libraries, from a disk vendor is like asking for advice on different types of bread from your butcher, or advice about various cuts of meat at the bakery.
The butchers and bakers might give you answers, but it may not be the best advice.
technorati tags: HDS, Hu Yoshida, Mark O'Gara, Highmark, SNW, Orlando, Florida, de-duplication, deduplication, dedupe, robotic, tape library, virtual, VTL, Clipper Group, David Reine, Mike Kahn, SATA, disk, systems, HP, Sun, backup, archive, workloads, butcher, baker, bakery, meat, bread, advice, IBM, Tivoli Storage Manager, TSM, LTO, LTO-4
Storage Networking World conference is over, and the buzz from the analysts appears to be focused onXiotech's low-cost RAID brick (LCRB) called Intelligent Storage Element, or ISE.
(Full disclosure: I work for IBM, not Xiotech, in case there weren't enough IBM references on this blog page to remindyou of that. I am writing this piece entirely from publicly available sources of information, and notfrom any internal working relationships between IBM and Xiotech. Xiotech is a member of the IBM BladeCenteralliance and our two companies collaborate together in that regard.)
Fellow blogger Jon Toigo in his DrunkenData blog posted [I’m Humming “ISE ISE Baby” this Week] and then a follow-up post[ISE Launches]. I looked up Xiotech's SPC-1benchmark numbers for the Emprise 5000 with both 73GB and 146GB drives, and at 8,202 IOPS per TB, does not seem to be as fast as IBM SAN VolumeControllers 11,354 IOPS per TB. Xiotech offers an impressive 5 year warranty (by comparison, IBM offers up to 4 years, and EMC I think is stillonly 90 days).Jon also wrote a review in [Enterprise Systems]that goes into more detail about the ISE.
Fellow blogger Robin Harris in his StorageMojo blog posted [SNW update - Xiotech’s ISE and the dilithium solution], feeling that Xiotech should win the "Best Announcement at SNW" prize. He points to the cool video on the[Xiotech website]. In that video, they claim 91,000 IOPS.Given that it took forty(40) 73GB drives (or 4 datapacs) in the previous example to get 8,202 IOPS for 1TB usable, I am guessing the 91,000 IOPS is probably 44 datapacs (440 drives) glommed together, representing 11TB usable.The ISE design appears very similar to the "data modules" used in IBM's XIV Nextra system.
Fellow blogger Mark Twomey from EMC in his StorageZilla blog posted[Xiotech: Industry second]correctly points out that Xiotech's 520-byte block (512 bytes plus extra for added integrity) was not the firstin the industry. Mark explains that EMC CLARiiON had this since the early 1990's, and implies in the title that this must have been the first in the industry, making Xiotech an industry second. Sorry Mark, both EMC and Xiotech were late to the game. IBM had been using 520-byte blocksize on its disk since 1980 with the System/38. This system morphed to the AS/400, and the blocksize was bumped up to 522 bytes in 1990, and is now called the System i, where the blocksize was bumped up yet again to 528 bytes in 2007.
While IBM was clever to do this, it actually means fewer choices for our System i clients, being only able to chooseexternal disk systems that explicitly support these non-standard blocksize values, such as the IBM System Storage DS8000and DS6000 series. (Yes, BarryB, IBM still sells the DS6000!) The DS6000 was specifically designed with the System i and smaller System z mainframes in mind, and in that niche does very well. Fortunately, as I mentioned in my February post [Getting off the island - the new i5/OS V6R1], IBM has now used virtualization, in the form of the VIOS logical partition, to allow i5/OS systems to attach to standard 512-byte block devices, greatly expanding the storage choices for our clients.
(Side note: SNW happens twice per year, so the challenge is having something new and fresh to talk about each time. While Andy Monshaw, General Manager of IBM System Storage, highlighted some of the many emerging technologies in his keynote address, IBM shipped on many of them prior to his last appearance in October 2007: thin provisioning in the IBM System Storage N series, deduplication in the IBM System Storage N series Advanced Single Instance Storage (A-SIS) feature, and Solid State Disk (SSD) drives in the IBM BladeCenter HS21-XM models. Of course, not everyone buys IBM gear the first day it is available, and IBM is not the only vendor to offer these technologies. My point is that for many people, these are still not yet deployed in their own data center, and so they are still in the future for them. However, since these IBM deliveries happened more than six months ago, they're old news in the eyes of the SNW attendees. While those who follow IBM closely would know that, others like[Britney Spears] may not.)
Back in the 1990s, when IBM was developing the IBM SAN Volume Controller (SVC), we generically called the managed disk arrays that were being virtualized by the SVC as "low-cost RAID brick" or LCRB. The IBM DS3400 is a good example of this. However, as we learned, SVC is not just for LCRB, it adds value in front of all kinds of disk systems, including the not-so-low-cost EMC DMX and IBM DS8000 disk systems. ISE might make a reasonable back-end managed disk device for IBM SVC to virtualize. This gives you the new cool features of Xiotech's ISE, with IBM SVC's faster performance, more robust functionality and advanced copy services.
Next week, I'll be in South America in meetings with IBM Business Partners and storage sales reps.
technorati tags: SNW, LCRB, Xiotech, ISE, IBM, BladeCenter, Jon Toigo, DrunkenData, Robin Harris, StorageMojo, SPC, SPC-1, SPC-2, Emprise, SAN Volume Controller, SVC, XIV, Nextra, Mark Twomey, StorageZilla, EMC, CLARiiON, System/38, AS/400, System i, i5/OS, V6R1, VIOS, Andy Monshaw, thin provisioning, N series, deduplication, de-dupe, A-SIS, SSD, HS21 XM, BarryB, Britney Spears, DMX, DS3400
Normally, IBM only makes announcements on Tuesdays, but today, Friday, IBM announces that it acquired Diligent Technologies. What? I got a lot ofquestions about this, so I thought I would start with this...
When I posted in January that[IBM Acquires XIV],fellow EMC blogger Mark Twomey of StorageZilla fame, sent me a comment:
"Ah now Tony I wasn't poking fun. Indeed I find it fascinating that Moshe who's been sitting out on the fringes for years having been banished for being an obstructionist to EMC entering the mid-market is now back.
Which reminds me what happens with Diligent? There his as well aren't they or has he packed his stake in that in?"
As you might have guessed, I am privy to a lot of stuff going on behind the scenes at IBM that I can't talk about in this blog, and all these rumors in the blogosphere about IBM acquisition of Diligent was a topic I couldn't officially recognize, defend or deny, until official IBM announcements were made.
In his latest post, Mark wonders about[the last Tape and Mainframe sales person on earth]. He recounts my interaction with fellow HDS blogger Hu Yoshia about the energy benefits ofVirtual Tape Libraries. Knowing that we were going to announcement IBM's acquisition of Diligent soon, I thoughtthis would be a worthy exchange, driving up the sales of Diligent boxes (whether you buy them from IBM or HDS).Diligent already had reselling arrangements with HDS, and IBM plans to continue thosearrangements going forward with HDS. As I have explained before in my post [Supermarketsand Specialty Shops], IBM and HDS cater to different customers, so if a customer who wants the best technologyfrom a specialty shop, they can buy IBM Diligent products from HDS, but if they want one-stop shopping, they can buyIBM Diligent directly from IBM or its other IBM Business Partners.
(Perhaps a more tricky situation is that Diligent also had an arrangement with Sun Microsystems, which competesdirectly against IBM as another IT supermarket vendor, but I have not heard how IBM has decided to handle thisgoing forward.)
For more on this intricate mess of interconnected companies, alliances and partnerships, read Dave Raffo's article[Data dedupe dance cardfilling up] over at Storage Soup.
So, let's tackle the first question:
- Q1. What will happen to IBM's real tape library business?
Come on! IBM is Number one in tape, we've had virtual tape libraries since 1997 (the first in the industry)and continue to do well in both virtual and real tape libraries. Both provide value to the customer, and bothhave their place as part of the overall "information infrastructure". This acquisition provides yet another choicefor clients on our "supermarket" shelf.
(For those following the ["which is greener"] discussion, the robot of the IBM TS3500 real tape library consumes185W per frame (when moving) and each tape drive consumes 50W (when actively working on a tape). Compared to 13W per SATA disk drive, each 6-drive frame of a TS3500 consumes as much electricity as 37 SATA disk drives. If you are not running backups 24x7, the total KWh per day for your tape library is actually quite less, but as several people have pointed out, there are customers that do run backups 80-90 percent of the time. LTO-4 tapes can hold 800GB uncompressed, and SATA disk are now available in 1TB (1000 GB) size, so you can have fun with your own comparisons.)
Meanwhile, Scott Waterhouse, one of the few people at EMC who understand tape workloadslike backup and archive, takes me to task in his Backup Blog
with his post[I want a Red Ferrari
].For those who are surprised that anyone at EMC might understand backup workloads, EMC did acquire a company calledLegato, and perhaps Scott came from that acquisition. I've never met Scott in person, but based solely only fromhis writings, he seems to know his stuff and makes strong arguments for using IBM Tivoli Storage Manager (TSM) with deduplication and virtual tape libraries.
While TSM does a good job of "deduplicating" at the client first, backing up only changed data, Scott feels database and email repositories must be backed up entirely each time, which is what happens in many other backup software products. Some clients might have 80 percent database/email and only 20 percent files, while others might have less than 20 percent database/email and 80 percent files, so this might influence whether deduplication will have small or big benefit.If TSM has to backup the entire database, even though little has changed since the last backup, that is where deduplication on a virtual tape library can come in handy. For IBM DB2 and Oracle databases, IBM TSM application-aware Tivoli Data Protection module interface backs up only changed data, not the entire file. Thanks to IBM's FilesX acquisition-- (also coincidently from Israel) --IBM can extend this support now to SQL Server databases as well.However, to be fair, Scott is partly correct, TSM does backup some database and email repositories in their entirety, which is why it is a good idea to have BOTH an IBM virtual tape library with deduplication and Tivoli Storage Manager to handle all cases. This brings us to the next question:
- Q2. What will happen to IBM's patented "progressive backup" technology?
IBM will continue to use TSM's progressive backup technology. TSM already works great with Diligent virtual tapelibraries. One example is LAN-free backup. In this configuration, the TSM client writes its backups directly toa virtual or real tape library, over the SAN, and then sends the list of files backed up to the TSM server over theLAN to record in its database. This can greatly reduce IP traffic on your LAN during peak backup periods. For more about this, see the IBM Redbook titled["Get More Out of Your SAN with IBM Tivoli Storage Manager"].
Jon Toigo from DrunkenData asks[Did IBM Do Due Diligence Before Making Diligent Acquisition a Done Deal?] which is probably always a valid question. Unlike XIV, I wasn't part of the Diligent acquisition team, so I can't provide first hand account of the process. I am told that the IBM team did all the right things to make sure everything is going to turn out right.Sadly, many companies that make acquisitions in the IT industry fail to make them work. Fortunately, IBM is one of the few companies that has a great success record, with over 60 acquisitions in the past six years.In the Xconomy forum, Wade Rousch writes[IBM and the Art of Acquisitions]and gives some insight why IBM is different. Jon did not understand why Cindy Grossman, IBM VP of tape and archive solutions, ran the analyst conference call for this announcement, which brings me to the next question:
- Q3. What is Diligent virtual tape library going to be categorized as, a disk system or a tape system?
IBM organizes its storage systems based on the host application workloads.Products to address disk workloads (SVC, DS8000 series, DS6000 series, DS4000 series, DS3000 series, N series, XIV Nextra) are in our disk systems group. Storage that appears to host applications like a tape system to address workloads like backup and archive (tape drives, libraries and tape virtualization) are in our tape and archive group. IBM Diligent has two products, one for big workloads and one for medium workloads. Both look liketape systems, so our tape and archive team, who understand tape workloads like backup and archive the best, are obviously the best choice to support IBM Diligent in the mix.
Some might remember that IBM already has deduplication in its IBM N series products, called Advanced Single InstanceStorage, or A-SIS. Here is an[IBM System Storage N Series A-SIS Deduplication Deployment and Implementation Guide. This brings up the fourth question:
- Q4. What will happen to N series A-SIS feature?
IBM will offer both N series and Diligent deduplication capabilities. For disk workloads, IBM N series offers a post-process deduplication feature at no additional charge. For tape workloads, IBM will now offer an in-line deduplication feature with Diligent Technologies. Different workloads, different offerings.
As with any acquisition, there will be some changes. The 100 folks from Diligent will get to learn the IBM wayof doing things. This brings me to our fifth and final question:
- Q5. What is the correct spelling: deduplication or de-duplication?
It appears that Diligent has a corporate-wide standard to hyphenate this term (de-duplication), but the "word police" at IBM that control and standardize all "proper spellings, trademarks, and capitalization" have sent me corporate instructions a few days ago that IBM does not to hyphenate this term (deduplication). So, going forward, it will be "deduplication", or "dedupe" for short.I suspect one of the first tasks that our new IBMers from Diligent will be doing is removing all those hyphens fromthe [Diligent Technologies website]!
That's all for now, I'm off to Chicago, Illinois tomorrow!
technorati tags: IBM, Diligent, acquisition, LOST, EMC, Mark Twomey, Moshe Yanai, Pam West, StorageZilla, HDS, Hu Yoshida, Sun Microsystems, virtual, real, tape library, VTL, SATA, LTO, LTO-4, TS3500, Scott Waterhouse, information infrastructure, email, database, backup, archive, Oracle, DB2, SQL Server, FilesX, SAN, LAN, IP, LAN-free, TSM, Tivoli Storage Manager, XIV, Nextra, A-SIS, Chicago, deduplication, Dave Raffo, dedupe
Well, today is April 1, and I just love [April Fools' Day
].This day has a rich history of practical jokes. Those not familiar can review this list of [Top 100 pranks and hoaxes
Tim Ferris started the festivities with [The Grand Illusion: The Real Tim Ferriss speaks]. He claimed that for the past year, he outsourced the writing of his blog to a writer from India, and an editor from the Philippines. Given that his post was dated March 31, and he writes frequently about the benefits of outsourcing, it appeared like a legitimate post. However, Tim fessed up the following day, claiming that it was April 1 in Japan where he wrote it.
Guy Kawasaki wrote[April Fools' Stories You Shouldn't Believe]including my favorite #12 "Ruby on Rails cited Twitter as the centerpiece of its new 'Rails Can Scale' marketing program." Speaking of Twitter, Fellow IBM blogger Alan Lepofsky from our Lotus Notes team wrote[Great, now there is Twitter Spam]. It looked like a real post, but then I realized, ... everything on Twitter is spam!
Topics like energy consumption and global warming were fodder for posts and pranks.The post[Was Earth Hour a joke again?], argued thatthe preparation of "Earth Hour" last week in effect used up more energy than the hour of this annual "lights-off event" actually saved. This reminded me of John Tierney's piece in the New York Times ["How virtuous is Ed Begley, Jr.?"] where a scientist explains that it is more "green" for the environment to drive a car short distances than to walk:
If you walk 1.5 miles, Mr. Goodall calculates, and replace those calories by drinking about a cup of milk, the greenhouse emissions connected with that milk (like methane from the dairy farm and carbon dioxide from the delivery truck) are just about equal to the emissions from a typical car making the same trip. And if there were two of you making the trip, then the car would definitely be the more planet-friendly way to go.
Wayan Vota, my buddy over at OLPCnews, writes in his post[Windows XO Child Centric Development] that the "Sugar" operating environment on the innovative Linux-based XO laptops will soon be re-named the"Windows XO Operating System", with their new motto "Windows XO: A Child-Centric Operating Platform for Learning, Expression and Exploration." The mocked up photo of an XO laptop with the Windows XO logo was excellent!
Gretchen Rubin reminds us that this is a great day to play tricks on your kids in[How April Fool’s day can be a source of happiness], and last week, Kai Ryssdal on NPR Radio investigated if [Mind Habits] was [a video game that's good for you?]This claims that just playing five minutes per day can reduce stress. I haven't been able to stop playing after five minutes, Mind Habits is like the proverbial potato chip, you can't just eat one!
The economists from Freakonomics explain in [And While You're at it, Toss the Nickel] that it costs the US Government 1.7 cents to produce each penny. The US government loses $50 million dollars each year making pennies. Each nickel costs 10 cents to produce. This one was dated March 31, so it could actually be true. Sad, but true.
My favorite, however, was EMC blogger Barry Burke's post["5773 > c"] explaining howtheir scientists were able to reduce latency on the EMC SRDF disk replication capability:
What the de-dupe team found is that there is a hidden feature within recent generations of this chip that allow a single bit, under certain circumstances, to represent TWO bits of information.
Still, almost 34% of the total bits transferred were in fact aligned double-zeros, far more than all other bit combinations - and most importantly, these were quite frequently byte-aligned, as required by this new-found capability. Makes sense, if you think about it - most of those 32- and 64-bit integers are used to store numbers that are relatively small (years, months, days, credit charges, account balances, etc.). So that's why the team decided to use this new two-fer bit to represent "00".
Mathematically, if you can transmit 34% of the data using half as many bits, you reduce the number of bits you have to transfer in total by 17%. Which, while not necessarily earth-shattering, is nothing to be ashamed of. On top of the SRDF performance enhancements delivered in 5772 (30% reduction in latency or 2x the distance), this new enhancement adds another 17% latency improvement (or ~1.4x more distance at the same latency). Combined with 5772, SRDF/S customers could see a 50% reduction in latency. And 5773 allows SRDF/A cycle times to be set below 5 seconds (with RPQ) - this new feature adds a little headroom to maximize bandwidth efficiency for the shortest possible RPO.
Again, this looked real, until I did the math. Start with the speed of light in a vacuum of space ("c" in BarryB's title) which is roughly 300,000 kilometers per second, or put into more understandable units, 300 kilometers per millisecond. However, light travels slower through all other materials, and for fiber optic glass it is only 200 kilometers per millisecond. Sending a block of data across 100km, and then getting a response back that it arrived safely, is a total round-trip distance of 200km, so roughly 1 millisecond. However, EMC SRDF often takes two or three round-trips per write, versus IBM Metro Mirror on the IBM System Storage DS8000 which has got this down to a single round-trip. The number of round-trips has a much bigger effect on latency than EMC's double-bit data compression technique. With IBM, you only experience about 1 millisecond latency per write for every 100km distance between locations, the shortest latency in the industry.
It is good that once a year, you should be skeptical of what you read in the blogosphere, and sometimes check the facts!
technorati tags: April Fools Day, Tim Ferris, 4HWW, outsourcing, Guy Kawasaki, Ruby on Rails, Twitter, Alan Lepofsky, Lotus, Notes, Earth Hour, spam, John Tierney, Ed Begley Jr., milk, carbon dioxide, Wayan Vota, OLPCnews, Windows XO, Gretchen Rubin, Kai Ryssdal, Freakonomics, NPR, Mind Habits, penny, nickel, EMC, BarryB, SRDF, IBM, DS8000, Metro Mirror, latency, fiber optic, speed of light
Modified by TonyPearson
Fellow blogger and cartoon writer Scott Adams writes in his Dilbert Blog
posts about the [Monte Hall problem
].Monte Hall was the host of the American game show Let's Make a Deal
. Here is an excerpt:
|"The set up is this. Game show host Monte Hall offers you three doors. One has a car behind it, which will be your prize if you guess that door. The other two doors have goats. In other words, you have a 1/3 chance of getting the car.|
You pick a door, but before it is opened to reveal what is behind it, Monte opens one of the doors you did NOT choose, which he knows has a goat behind it. And he asks if you want to stick with your first choice or move to the other closed door. One of those two doors has a car behind it. Monte knows which one but you don’t."
Mathematically, on your initial choice of doors, you have a 1/3 chance of picking the car, and 2/3 chance ofpicking a goat. But, after you make a choice, Monte knows which door(s) have goats behind them, and selectsone that exposes the goat. If you stay with your initial choice, you still have a 1/3 chance that you win acar, but if you change your mind and choose the other door, your odds double, you have a 2/3 chance of winning.This is not obvious at all to most people, so Scott points people to the [Wikipedia entry] that provides the mathematicaldetails.
What does this have to do with storage?
When you pick a disk system, you are hoping you pick the door with the car. You want a disk system that meets your performance requirements for your particular workload and easy to deploy, configure and manage, with a low total cost of ownership for the three, four or five years you plan to use it.However, with over forty different storage vendors, there are some doors that might have goats. Some vendorshave only 90 day warranties for their software, and I don't know any customers that replace their disk systems that often.
(It was pointed out to me that it was unfair in my last week's post about[Xiotech'slow cost RAID brick], that I singled out EMC offering minuscule 90day warranties for the software needed to run their disk systems. I apologize. I have sincelearned that HDS and HP also shaft their clients with 90 day warranties. Apparently thereare a lot of vendors out there who lack confidence in the quality of their software!)
It would be nice if everyone published all of their performance benchmarks so that you canchoose the right door with the car behind it, but sadly in the storage industry, not everyoneparticipates with industry-standard benchmarks like the[Storage Performance Council].
In other cases, people make their choices based on past decisions. Perhaps someone beforethem chose one vendor over another, and it seems simple enough just to stay with the originalchoice. It is amazing how often people stay with their company's original choice, what we call in the industry the "incumbent vendor", without exploring alternatives.
So, if you bought an EMC, HDS or HP disk system in the last 90 days, it's not too late for you.Tell your local IBM rep that you are afraid you picked the door with the goat, and that you want to change your mind, and choose the other door and go with IBM instead.
You will double your chances of being happier with your new choice!
technorati tags: Scott Adams, Dilbert, Monte Hall, probability, 90-day, warranty, disk, system, benchmarks, SPC, SPC-1, SPC-2, game show, HDS, HP, IBM, goat, door, car