Opinion

The State of the SAN Array Market

posted on 09 August 2008 09:52

What clients need are integrated, functional systems that meet their requirements

Here is a personal opinion about the state of the SAN array market by a man with a clear product preference. His points aren't UK-specific at all and are relevant to SAN owners and buyers in the USA, Canada, Australia, wherever. Even if you disagree with the product preference at the end of his text the points he makes seem to us to be realistic, interesting and clearly put. They might help you cut through the mounds of marketing hype you may be receiving.

Richard Blanford (pictured left) is the managing director of Fordway Solutions, a UK-based network infrastructure specialist firm. Here is his view about the SAN array market:-

The State of the SAN Array Market

We’ve been providing SANs and consolidated storage solutions for 6 years. In that time we have supplied, installed and support SAN environments for over 100 clients across a wide range of industry sectors. Over this time we’ve worked with a variety of SAN vendors. In our view a few vendors are close to getting it right, while several are pursuing strategies that would appear to be more in the vendor's interest that their clients’.

What clients need are integrated, functional systems that meet their requirements, can scale easily without the need to rip out and replace controllers every couple of years, and provide useful functionality that is better than they can get from the disks they can buy with their servers.

Fibre channel or Ethernet/iSCSI?

Simple: why try and prove that one is better than the other? A good SAN array should offer both, and without swingeing financial penalties for choosing one or the other. Fibre channel still offers the highest performance readily available today and is optimised for high performance data transfers; iSCSI is a very cost effective method of connecting less critical or performance intensive servers but has a higher overhead. 10Gbps iSCSI takes away most of these limitations but is only just becoming available and currently is artificially expensive. Fibre Channel over Ethernet may just be the eventual winner but needs to become readily available, standardised and cost effective.

Proprietary Hardware

Modern servers are powerful, cheap and reliable. Most SAN vendors put artificial constraints and limitations on this, which may be to their benefit but rarely to the clients. Why force clients to choose arrays in specific sized versions, or standard size chunks, and force them to upgrade controllers and software licences or buy the whole chunk and licences again should their data grow faster than they expect or could afford at the time of purchase?

A PCI Express bus can transfer data pretty much as fast as anyone needs (2.5Gbps per channel at last count), so why design proprietary hardware and charge 4 times market rate for it? Also, if you use standard hardware you can simply slot in the 10Gbps iSCSI or FCoE card when it becomes available. Now wouldn’t that be nice?

Blocks or Files?

One of the key debates over the past few years is which is better, blocks or files? The simple answer is neither, clients need both. Vendors who have expertise in file systems have spent years trying to convince us that all data belongs in a file, even to the extent of making file systems emulate block storage with the commensurate overhead and then provide lesser functionality for the block storage. Why?

Functionality

What would be really useful?
- A SAN array that knew how old your data was, and automatically migrated it to cheaper disks without any intervention on your part and with no impact on the application or operating system?
- That allowed you to scale from 1TB to 500TB without needing to rip out and replace the controllers?
- That allowed you to allocate as much space as you thought you may ever need but only formats and uses the disk space as the actual data grows, for both block or file storage?
- That is proven to save money, use less resources and halved your operating and management costs?
- That allowed unlimited snapshots to be taken from each volume, without needing to reserve dedicated disk space that you may not need, or limiting you to 8 or 16 per volume?
- Also, why not make them mountable to other systems as soon as they were taken?
- Would replication built in to the controllers be useful, and while we’re at it how about allowing both one to many replication and many to one?

Thankfully for us and our clients this exists today, it’s called Compellent’s Storage Centre. Whilst most other vendors offer some of this functionality today, we believe this to be the only one with the full capability described above today. You may not yet have heard of it, but if you are serious about looking at the best option and not strung up on big vendors or brand name, we think it will be worth your while.

^{[Richard Blanford, Fordway:}^{http://www.fordway.com}^.]