In general, people agree that IBM, HP and EMC are the top three vendors in storage,with HDS, Sun and Dell rounding out the top six.
The fun begins when a respected analyst like IDC Corp. publishes their calculations,and individual vendors re-swizzle the results because they are not happy with theirfindings.
I thought it would be helpful to illustrate how this all works. First, you need to comeup with a defintion of what you are going to count. You could count units sold, revenue dollars, or capacity Terabytes, or some other generally accepted metric.
Next, you need to define what's in and what's out. For example, you can say "storage"which would include both disk drives and tape drives, both internal to servers, orexternal to servers, or you can choose a more narrow definition, say external disksystems, which might suit you better if you aren't in the tape business, and don't sell servers.
By some definitions, my Apple iPod, Motorolla cell phone, and Canon digital camera,could all be counted as external disk systems, as they all connect via USB cableto my IBM laptop, and act like a disk drive to my Windows operating system, allowingme to read and write data back and forth. It is necessary to define exactly what you plan to include,and what to exclude, based on the reported numbers available.
The last rule is that nothing gets double-counted. In our complicated industry ofmanufacturers and vendors, sometimes storage is manufactured by one company, but soldby another, typically under the vendor's brand, not the manufacturer's brand. Youcan either count manufactured units, or vendor units, but you can't mix and match.
IBM is both manufacturer and vendor. However, IDC only counts vendor units, so storagemanufactured by someone else, but sold by IBM is counted as IBM, and storage manufacturedby IBM but branded by someone else goes to that other vendor. Likewise, HP and Sun re-brandHitachi storage, and Dell re-brands EMC storage.
EMC would like to treat all EMC-manufactured storage re-branded by Dell as EMC vended storage,so that it can move up in the ratings. But Dell wants to count it too, so that it can appearin the top six. You can't have it both ways.
But are these ratings just "bragging rights"? Not always. When big purchases are planned fornew projects, or a client decides its time to throw out the current vendor and shop for a newone, the ratings could influence that decision. In that regard, IDC 4Q05 Storage Tracker reportedIBM as number one over all in storage hardware at the end of 2005, which includes both internal and external disk systems, as well as tape drives sold under the IBM brand, based on dollar revenues. By this method of counting, HP came in at number 2, EMC at number 3, and the rest round out thetop six as before.
In the end, this is just one factor when deciding which brand to choose for your storage needs.