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How DBAs view storage

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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

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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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