Storage Management with Overdraft Protection

Hands On: W. Quinn Associates' QuotaAdvisor and DiskAdvisor

Disk quota services have been a long-missing, and long overdue, gap in user services with Microsoft Corp.'s Windows NT Server. Unlike NetWare, which offers easy-to-administer accounting controls, NT Server has never offered any native means of controlling disk space utilization.

The QuotaAdvisor and DiskAdvisor products in the StorageCentral suite from W. Quinn Associates Inc. help fill this important need. The products are available as part of the product suite or individually.

QuotaAdvisor 4.0, the linchpin of StorageCentral, monitors and enforces disk quotas across multiple partitions, directories and file sets. The product is capable of learning patterns, watching trends of usage and has wizard controls for easy operations.

DiskAdvisor 4.0 performs standard and customizable reports on disk usage, trending, wasted space, and related information.

Also included in StorageCentral is DiskWatcher 4.0. This product performs partition-level monitoring of resources. DiskWatcher doesn't provide any enforcement, but monitors and evaluates partition performance for future regulation or limitations.

StorageCentral comes with three printed manuals for each of its services, and one CD-ROM disk.

We tested Quota Advisor on a Windows NT Server 4.0 machine with Service Pack 4 running on a dual-processor Pentium 200 with 256 MB of memory and Fast SCSI-2 disk drives. It was attached to a switched, 100-Mbps fiber optic Ethernet backbone. We created a new machine with NT 4.0 and SP4 for test purposes, and placed it on the opposite side of the network so we could test performance across a routed environment.


The installation of each product took less than 15 minutes, and oddly -- but much to our delight -- didn't require a reboot of the server. Slightly more than 20 MB of disk space was consumed after the installation for the program files, and another 5 MB to 10 MB during reporting runs. Using just under 2 MB of physical memory, the processes for disk controls swiftly took control of the disk resources.

We first looked at QuotaAdvisor and found a clean and efficient menu system. It offers a wizard to guide novices through the quota establishment procedures, which are quite simple.

We created a set of limitations for our FTP test server that topped out at 1 GB of disk space. This applied to all FTP users. Quota management can be specified based on individual user's home directories or as a global assignment -- as we chose to implement. These assignments can be floating so they can grow with disk space, or can be absolute limitations. You have the additional option to grant users specific amounts of "overdraft" protection.

This overdraft capability is useful in certain scenarios. Let's say you run an ISP service and you allocate 50 MB of disk space to each user. One of these users happens to be a valued client with whom you frequently transact business. If their current use is set at 45 MB, and they have a file that is 7 MB in size, they'd be out of luck if you chopped them off at exactly 50 MB. If you give them a 10 percent overage allowance, they can, on a temporary basis, go over their limit. This protection is transparent to the user, but the administrator can be notified via e-mail or through a pop-up message that warns about the condition. Log files also record the condition.

Reporting Tools

The reporting tools in DiskAdvisor are really easy to use and adjust for changing conditions. We found tools that provided details such as which files have never been accessed and which ones register the most access. One tool we found particularly valuable: When you run Windows Explorer, bringing up the properties of the directory told us at a glance how much space is being used out of the total quota.

The reporting tools in DiskAdvisor are easy to use and easy to configure. We found them to accurately report on quotas and other valuable storage information.

One useful DiskAdvisor query checks on file systems. If you had a huge FTP server and wanted to clean out old and unused files, DiskAdvisor can scan the file structure according to your specific needs. We asked DiskAdvisor to find all files larger than 5 MB in size that had not been accessed in the last 180 days. We were surprised to find files we thought we had trashed during our last purge.

Overall, we found QuotaAdvisor and DiskAdvisor to be solid performers and a solid value. We didn't run across any measurable problems during the review period. We believe this product demonstrates a version-4 maturity level and stability that should exist with any product that serves such a critical need.

What About Windows 2000?

One of the features integrated into Windows 2000 is a limited set of quota management features. Those capabilities appear to lessen the need for quota management products such as those provided with StorageCentral. Representatives of W. Quinn Associates counter that argument by stating that Windows 2000 will offer quota management only on a volume-by-volume basis, which won't provide the user-level granularity that existing third-party products offer. They also claim the Microsoft OS will not offer the sophistication of usage reports. Perhaps the best validation of that argument is a recent three-year deal that W. Quinn signed with Microsoft, where Microsoft will deploy QuotaAdvisor on a worldwide basis in its corporate data centers. -- Al Gillen

QuotaAdvisor 4.0 and DiskAdvisor 4.0
W. Quinn Associates Inc.
Reston, Va.
(800) 829-3453
(703) 758-0707

Price: Single server license of $995 for DiskAdvisor and QuotaAdvisor. Other licensing available depending on configuration.

+ Easy, intuitive user interface
+ Overdraft protection feature
+ Good integration between quota management tools and reporting tools

- Faces competition from built-in Windows 2000 quota management capabilities
- Menu system needs some minor refinements
- Online help could be more detailed

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