How DBAs view storage

Storage magazine's exclusive poll gives you the lowdown on how DBAs and storage pros view storage. We detail each group's areas of concern, spotlight their differences and find some common ground.

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You're on the way to a kickoff meeting for a new CRM project that requires back-end storage which, as the storage administrator, you must supply. You recall conversations with some of the database administrators (DBAs) about the requirements--approximately 2TB--which you feel can be done without breaking your budget. The meeting is attended by several DBAs, the project manger (PM), a few DBA/software contractors representing the vendor and a sales representative you've never seen before.

Before you can say "ambush," the DBAs bombard you with unrealistic disk requirements and configurations, and the PM scratches your name on the Gantt chart, but quickly adds that there are no additional funds in the budget for storage hardware. On your way out, you're reminded that the progress of this project will be monitored at the highest levels in the company.

If this fictional scenario touches a nerve, there's a reason. As technology progresses, storage allocation is becoming less of a mystery. Advances in software allow groups outside the storage team, such as DBAs, to allocate and automate storage. For example, the Automated Storage Management feature in Oracle 10g allows DBAs to allocate storage from a pool of storage at their discretion, and without involving a server or storage resource.

So, do DBAs want to be storage administrators? Probably not. However, as a storage admin, you'll need to decide what DBAs expect from detached storage and how involved they want to be with the storage systems that support their apps. Of course, storage responsibilities vary from company to company, as do the job descriptions that go with storage and DBA job titles. In an effort to understand the DBA-storage admin dynamic, we surveyed DBAs and storage admins at various companies and asked them about their storage systems, configurations and personal preferences.

DBAs and storage admins agree...somewhat

Survey results
To start, DBAs and storage administrators were asked to rate the following criteria on a scale of one to 10, with one being "No concern" and 10 being "Highest concern." The criteria included:

  • Backup windows
  • Costs
  • Disaster recovery (DR)/recoverability
  • Performance
  • Proprietary hardware/software features
  • Redundancy
  • Service level agreements (SLAs) (vendor related)
  • Storage tiers
  • Uptime

We found DBAs rated their highest concern as uptime, followed by performance, redundancy and DR/recoverability (see "DBAs and storage admins agree ... somewhat," this page). While redundancy increases uptime, it doesn't guarantee it, which is why they're separate issues. Most DBAs would rather have a system up and performing slowly, or operating in a degraded state, than not functioning at all. The average score for each of these four DBA priority issues was eight or above; vendor SLAs, storage tiers and proprietary hardware/software features netted average scores of five or higher (many of the DBAs whose companies had storage teams didn't know what tiering was).

Not surprisingly, storage administrators' responses were similar. Uptime, performance, redundancy and DR/recoverability all scored an eight or above, while proprietary hardware/software features, backup windows and storage tiers received average scores above seven. Scores for SLAs and cost were in the six range. In addition, some storage admins felt scalability was a key factor that should have been included in the list.

The next survey question dealt with disk subsystems and asked: "When selecting a storage solution, what matters most to you?" We used the same one-to-10 scale, with one meaning "Doesn't matter" and 10 indicating "Matters a lot." The criteria evaluated included:

  • Budget/cost
  • Drive type, quantity, capacity
  • Existing relationships with vendors
  • Management direction
  • Manufacturer name/reputation
  • Manufacturer warranty/service ability
  • Past experience with hardware
  • Proprietary software for management, reporting, failover, etc.
  • RAID types
  • Redundant connectivity to the data
  • Redundant hardware in the disk subsystem
  • System cache

In this area, DBAs are more concerned with management direction than storage admins are (see What matters most, this page). To them, what matters is how the hardware will evolve, familiarity with the hardware (past experience), system cache and whether, in case of a disk failure, there's redundant hardware in the disk subsystem. While there was some general agreement between the two groups, the response differences may be attributed to DBAs having been taught that spindle size, spindle count and cache are directly proportionate to better performance. While this might have been a general rule some time ago, it's not always the case now. Yet for high-end storage configurations, large quantities of small-sized disk, front-ended with gobs of cache in a dedicated disk subsystem, will certainly help to resolve any I/O performance issues.

There are stories of companies purchasing large-capacity disk drives and allocating only 8GB of the total (4GB above and 4GB below the heads' resting positions) to increase spindle count and limit head movement, which is an expensive way to cut down on single-drive I/O bottlenecks. With an eye toward improving performance, some manufacturers have proprietary software packages that analyze the I/O for bottlenecks on individual disk drives and then modify the disk subsystem's configuration to eliminate the bottlenecks. EMC Corp.'s Optimizer, for example, can be configured to detect "hot spots" and automatically move data from highly used disks to disks with low I/O in an effort to limit I/O bottlenecks.

What matters most

The purchase criteria the two camps differed on the most was "proprietary software for management, reporting, failover, etc." This was probably because of DBAs' lack of knowledge regarding proprietary storage tools, such as EMC's Optimizer. DBAs typically aren't exposed to such tools, so it's no surprise that they rated this issue as a lower priority than storage administrators did.

"Existing relationships with vendors" had the next-highest ratings difference between the two groups. This was something of a surprise because DBAs generally have a high product and vendor loyalty. Because of that loyalty, one would have expected DBAs to rate this criteria at least as high as storage professionals did. On the other hand, storage admins are often required to interact with multiple vendors and may leverage those vendor relationships more for planning and troubleshooting than their DBA counterparts do.

Who are the decision-makers?
The next series of questions dealt with internal and external influences on the decision-making processes related to storage systems. There were three questions:

  • Who makes storage recommendations for your environment?
  • Who designs/configures storage systems for your environment?
  • Who designs/configures database systems for your environment?

For each of these questions, respondents were asked to rate the level of involvement of senior management, storage teams, DBAs, server teams, contractors and vendors as "Never," "Sometimes provides input," "Often" and "Always." The involvement of senior management varied by company, rather than by project or groups; this was probably due to an individual firm's corporate culture and the procedures it follows.

Most companies rely on vendors and contractors to work with the storage and server teams to recommend storage solutions. Companies without designated storage teams rely heavily on the server teams to make storage recommendations. Most DBAs aren't actively involved in making storage recommendations.

Vendors, contractors, and storage and server teams are almost always involved with the design and/or configuration of storage systems. Vendors and contractors are typically more actively engaged during those activities than in the recommendation process.

When designing databases, most DBAs rely heavily on their own team's abilities, sometimes seeking the expertise of vendors, contractors, and storage and server resources. Some DBAs said they also work heavily with application and development teams to determine what hardware requirements are necessary, and then involve server and storage staff to fulfill those requests.

An interesting point to note is that the responses from DBAs working for companies with dedicated storage teams varied from the responses from DBAs whose companies lack dedicated storage staffs. DBAs at companies without dedicated storage administrators paid more attention to storage systems than those with dedicated storage administrators. DBAs working for companies with storage teams didn't care as much about RAID types, SLAs and storage tiers, and were less likely to be involved with storage-related decisions. Overall, the results indicate that DBAs expect the storage team to monitor performance and build redundancy into storage systems to meet uptime requirements.

No turf war in sight
If you're a storage administrator, don't worry about DBAs eyeing your territory. The vast majority of DBAs interviewed who work for companies with designated storage teams see storage as a device they connect to, and they want little to do with it as long as it's not slowing their databases down. Furthermore, DBAs typically interact with server admins rather than storage admins for initial configurations and enjoy not having to shoulder the burden of storage management.

This was first published in July 2005
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