Five Storage Strategies that *May* Save You Money

Infoworld have a great article here discussing how to save money on storage in these tight times we are experiencing. Here's a summary - with my opinions of course!

1. Play Hardball with Vendors. Ah if it was only that simple. It may be possible to find another vendor selling hardware marginally cheaper, but are you ready for it? There are few companies who have got their storage deployment to a level where interoperability allows them to take storage from any of a range of vendors. Fewer still who have calculated the cost of migration or the full operating expense for each vendor's product; it isn't all about the hardware cost alone.


2. Avoid New Purchases By Reclaiming What You Have. So what tools will you use to achieve this? Do you know how and why you are missing storage which can be reclaimed? Storage reclamation is usually an ad-hoc process run when storage gets tight or when admins have the time. Some places may have written scripts to automate the discovery of wastage but it isn't easy. I use my own software tool and can highlight about 10 separate categories but you need to be careful of the law of diminishing returns.


3. Audit Backup and Replication Configurations To Cut Waste. Right, so throw away some backups. Are you *sure* you can do that? Surely the data owner needs to validate whether that backup copy isn't needed any longer...


4. Rethink Storage Network Decisions. I like this one. Basically, find a cheaper piece of hardware - which may include DAS! Again, interoperability and migration costs have a big impact here. Any marginal savings may be wiped out by the cost of moving to another platform.


5. Use a Tiering Methodology That Delivers Results Simply. Finally a point I agree with. Tiering can be implemented easily by taking a common sense approach to moving data to a cheaper layer of disk. This doesn't have to involve a migration project but can be achieved as users request more storage.

All of these options are great, however they fail to attack the underlying issue of rising costs - that fact that more data is being generated each day. Simply asking users to question whether new storage is needed or existing allocations can be re-used is as easy as implementing new technical solutions.

Remember - keep it simple!

Developing a Tiering Strategy

Implementing a storage tiering strategy is a big thing these days. Everyone should do it. If you don't then you're not a "proper" storage administrator. Being serious and moving away from the hype for a second, there is a lot of sense in implementing tiering. It comes down to 1 thing - cost. If disk and tape storage was free, we'd place all our data on the fastest media. Unfortunately storage isn't free and therefore matching data value to storage tiers is an effective way of saving money.

Choosing the Metrics

In order to create tiers it's necessary to set the metrics that define different tiers of storage. There are many to choose from:

• Response time
• Throughput
• Availability (e.g. 5 9's)
• Disk Geometry (73/146/300/500GB)
• Disk interconnection (SATA/FC/SCSI)
• Usage profile (Serial/Random)
• Access Profile (24x7, infrequent)
• Data value
• Array Type (modular/enteprise)
• Protection (RAID levels)

There are easily more, but these give you a flavour of what could be selected. In reality, to determine the metrics to use, you really need to look at what would act as a differentiator in your environment. For example, would it be really necessary to use 15K speed drives rather than 10K? Is availability important - should RAID6 be considered over RAID5? Is there data in the organisation that would exist happily on SATA drives rather than fibre channel? Choosing the metrics is a difficult call to make as it relies on knowing your environment to a high degree.

There are also a number of other options to consider. Tiers may be used to differentiate functionality, for example tiers could be used to specify whether remote replication or point-in-time copies are permitted.

Is It Worth It?

Once you've outlined the tiers to implement, you have to ask a simple question - will people use the storage tiers you've chosen? Tiering only works if you can retain a high usage percentage of the storage you deploy - it's no use deploying 20TB of one tier of storage and only using 10% of it. This is a key factor. There will be a minimum footprint and capacity which must be purchased for each tier and unless you can guarantee that storage will be used, any saving from tiering may be negated by unused resources. Narrow your tiering choices down to those you think are actually practical to implement.

Making the Move

So, the tiers are set, storage has been evaluated and migration targets have been identified. How do you make it worthwhile for your customers to migrate? Again, things come back to cost. Tiers of storage will attract differing costs for the customer and calculating and identifying the cost savings will provide a justification for investing in the migration. In addition, tiers can be introduced as part of a standard technology refresh - a process that regularly happens anyway.

Gotcha!

There are always going to be pitfalls with implementing tiering:

1. Don't get left with unusable resources. It may be appealing to identify lots of storage which can be pushed to a lower tier. However, if the existing tier of storage is not end-of-life or unless you have customers for it, you could end up with a lot of high tier unused storage which reflects badly on your efficiency targets. Make sure new storage brought in for tiering doesn't impact your overall storage usage efficiency.
2. Avoid implementing technology specific tiers which may change over time. One example; it is popular to choose to tier by drive size on the assumption that higher capacity drives offer a lower performance and therefore are matched to a lower tier. But what happens when the predominant drive type changes or you buy a new array in which the larger drives perform equally well compared to an older array? How should those tiers be classified?
3. Be careful when choosing absolute parameters for tiers. For example, it is tempting to quote response time characteristics in tiers. However, no subsystem can guarantee consistent response times. It may be more appropriate to set confidence limits, such as offering "<>

Iterative Process

Developing a tiering strategy is an iterative process which will constantly be refined over time. There's no doubt, that implemented correctly, it will save money. Just don't implement it and forget about it.