CEB Electronic X-ray Archive (EXA)
The Electronix X-ray Archive (EXA) will provide access to the NHANES image collection stored in either compressed or uncompressed form. It will be implemented incrementally with one or more optical disk jukeboxesand possibly a Redundant Array of Inexpensive Disks (RAIDs). The archive will be centrally located at the NLM and will be expandable toa capacity capable of hosting the entire collection of about 27,000 images, approximately 240 GBytes. Initially we will archive the NHANES II collection which has storage requirement estimated as follows:
| Uncompressed NHANES II Digitized Images |
| Image Type |
Dimensions (h×w) |
Bits/pixel |
Bytes/pixel |
Bytes/image |
| Cervical Spine |
1755×1463 |
12 |
2 |
5,135,130 |
| Lumbar Spine |
2487×2048 |
12 |
2 |
10,186,752 |
| Number of Images |
Bytes/image |
Total Bytes |
| 5,100 cervical spine |
5,135,130 |
26.189 GBytes |
| 11,900 lumbar spine |
10,186,752 |
121.222 GBytes |
| Total: 147.411 GBytes |
The design objectives of the EXA are:
1. It should have a maximum local access time of 10 seconds to any
file on any volume (optical disk) once the file has been identified.
2. It should be modular and expandable so that it can be
implmented incrementally as the collection increases in size.
3. It should support ANSI standard media, UNIX file format, SCSI
2.0 connectivity, and NFS.
4. The archive software should be capable of handling both online
media (within the jukebox) as well as offline media (stored on an
adjacent shelf).
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