Case Study: Police Service of Northern Ireland (PSNI)
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Company Overview
The Crime Scene Photography Branch of the Police Service of Northern Ireland (PSNI) manages more than 4,000 crime scene photos every month. Traditionally, the negatives of all those photos were stored in filing cabinets and taken out every time reprints were requested. Over the course of a criminal case and subsequent civil actions, the negatives could be handled many times to make from 3 to 20 reprints of each negative on each occasion. "We were going back time and time again to take out the negatives, handle them, reprint them, and file them away," explains PSNI's Head of Photography. "It was very, very labor intensive and could have had a detrimental effect on the negatives themselves, not to mention it increased the risk of the images being misfiled."
Like many policing organizations, PSNI runs on a tight budget and is constantly looking for ways to increase efficiency while maintaining the highest quality of professional policing. To support those goals, the PSNI Crime Scene Photography Branch decided to implement a digital storage system for all of its images. This system would make locating and getting reprints of the images faster, while eliminating the need to touch the negatives. The PSNI information technology (IT) staff originally set up a server with five 18-gigabyte (GB) hard disks to store the images, but that storage was soon exhausted, and the staff had to constantly move cases onto a tape backup and delete them from the hard disks.
Business Challenge
What the photo library really needed was a solution that could offer multiterabytes of storage—with the size of any one image ranging from 1.5 to 3.5 MB—as well as search and retrieval capabilities. The second requirement was that the storage provide online search and retrieval capabilities so that images needed by investigators could be quickly located and printed. The third requirement was an affordable price.
PSNI looked at a variety of solutions but none fully matched the requirements:
| • | A CD jukebox storage and recovery system. The 650-MB storage limitation on each CD did not provide the volume of storage required. |
| • | A DVD system. These systems provided more storage than the CD systems but didn't provide true online storage. There was a good chance that required images might not be loaded in the DVD when they were needed, so the time required to load the DVD in the jukebox would delay access to the images. Also, the read speeds of the DVD were very slow compared to those of a hard-disk drive. |
| • | SCSI RAID systems. At a cost ranging from GBP£50,000 to £150,000 (U.S. $78,800 to $236,400), these solutions were beyond the budget. |
| • | Digital tape storage. PSNI purchased a Sony AIT-2 Tape Library with 16 tape cartridges. A chip on each tape "remembers" what files were written to that tape. This solution came closer to the budget but didn't provide the storage capacity or the online functionality that PSNI wanted. |
After evaluating these solutions and finding that none of them met all of its requirements, PSNI became aware of the Windows® Powered network attached storage (NAS) solution. Running the optimized version of the Microsoft® Windows 2000 operating system, the Windows Powered NAS met PSNI's requirements for scalability, reliability, data protection, ease of setup and management, and interoperability with the photo library's existing applications, which include a legacy UNIX database. The Windows Powered NAS also offered a better cost per megabyte ratio than did the other solutions considered.
Solution
The Windows Powered NAS solution consists of two Intel-based servers, each with a RAID array of eight 160-GB hard disks, adding up to more than 2 terabytes of disk storage space. The array can expand to 15 hard disk units (with eight hard disks each) for each server or a total of 16.8 terabytes. The servers use the network load-balancing functionality in Windows 2000 Advanced Server to ensure higher performance and help protect against hardware failures. The NAS also interoperates with the Microsoft Windows NT® 4.0 Primary Domain Controller (PDC), which controls the PSNI photography branch domain.
The crime scene photos are scanned on a film scanner and stored in the Windows Powered NAS. Multiple authorized users can access the system at the same time, scanning image files into the system, searching and retrieving images, and downloading and printing photos.
The initial record of the file is created in a TRACER database that runs on the Windows NT-based PDC. All additional operations that involve the digital image, such as capturing, editing, and printing, are recorded by HALSE Pro Edit software on a Microsoft SQL ServerTM 2000 database running on a separate standalone Dell PC. This database records each time an image is printed and Windows 2000 Group Policy settings keep records of who has accessed and printed images from the Windows Powered NAS.
Users locate task records and look at thumbnails or full images using the TRACER database. "A routine is written into the database that directs it to the job folder and then brings up all the thumbnail images connected with that folder or job number from the NAS," says PSNI's Head of Photography. Once users have the thumbnail images, they can click that image to retrieve the full-size image and print it.
Business Benefits
Scalable Storage at a Low Cost Per Megabyte
The Windows Powered NAS solution provides PSNI with the storage it needs now and sets the stage for easily and economically expanding that storage as needed. The Windows Powered NAS is configured so that when PSNI needs additional storage, instead of purchasing another server, it can just add external hard disk units to the rack. Each server can take up to 15 hard disk units, each with up to eight hard disks.
This modular approach will enable PSNI to take advantage of the decreasing cost of hard disks. "We've not yet bought the additional disks because we've got enough elbow room for now," says PSNI's Head of Photography. "The additional storage for the Windows Powered NAS is quite cheap, so when we get close to filling up what we've got, we'll just pop in the additional disks. We estimate that this solution ran about 10 percent the cost of the nearest alternative that we originally considered."
Also, because the Windows Powered NAS integrates easily into PSNI's infrastructure, it saves the cost of integration, new software, and training of both IT staff and users.
Quick Image Retrieval Without the Risk of Damaging Negatives
PSNI administrators control who has access to the Windows Powered NAS image library and which resources authorized investigators can access. This provides easy 24-hour access to those who need it, while ensuring the integrity of the images and protecting the original negatives from damage or loss. The online system makes it easier for investigators and prosecutors to view the images as many times as they need to without having to handle the negatives. Eventually, when the PSNI intranet is installed, authorized users will be able to check out the images through a process somewhat like online shopping, so that they will be able to view the images from their own desktops.
Before the online storage solution was set up, those investigating and prosecuting cases had to send someone to pick up photos or wait for them to be delivered. That involved a lot of extra time, which could delay cases.
"We're becoming more and more reliant on the Windows Powered NAS to help ensure that the investigation and trial process proceeds in a timely manner," says PSNI's Head of Photography.
Increased Efficiency, Reduced Labor
The previous process of retrieving images from the original negatives required two people—a custodian as well as the person requesting the negatives. With the Windows Powered NAS, access is controlled through the software, so only authorized users are allowed to add, access, or print images. This eliminates the need for the second person and speeds the process considerably.
While the Windows Powered NAS was installed and configured quickly, other parts of the digital image library took longer. "I figured that it would take us roughly six weeks to clear out the backlog, working the hours that we could spare and using the original equipment that we had," says PSNI's Head of Photography. "With the Windows Powered NAS and our Kodak scanner and digital photographic printer, we actually cleared the backlog in nine days, very comfortably. Actually, nearly 90 percent of the scanning and printing work was done in the first weekend."
The NAS also requires virtually no extra management. "The Windows Powered NAS has eliminated the bottlenecks from the servers so the images are moved much more quickly," says PSNI's Head of Photography.
For more information, visit the Police Service of Northern Ireland Web site.
