DFN observatory data folders and files structure

Each DFN observatory has several disks with partitions for data. The operating system and buffer for several nights of data is on a fast and low power SSD drive, typically 500GB size. Most of it's size is allocated to data0 partition. This one is mounted as /data0 in the embedded PC OS filesystem. Last up to two nights of raw data plus all history of log files are typically stored in /data0.

On top of that, to be able to hold moths or years of data, there are removable drives. The number of drives depends on the observatory type. DFNKITs have just one drive (permanently powered), DFNSMALLs two drives and DFNEXTs three drives. These are mounted as /data1, /data2 and /data3. Every day in late morning the SW in the observatory moves all the data except last night from the /data0 buffer to the removable (archive) drives. They fill up from #1 to #3.

For DFNSMALLs and DFNEXTs, one needs to power up and mount the removable drives, eg using web GUI or commandline.

commandline example:

python /opt/dfn-software/enable_ext-hd.py
mount /data1
mount /data2
mount /data3
... access data
python /opt/dfn-software/disable_ext-hd.py

Note: It is essential to power off the HDDs when finished with data transfer!

Note: When they get completely full, the SW starts compressing the old data - converting rwa (.NEF) images to .jpg, but only those images, where event detection was successfully executed and did not detect any likely fireball event. This compression functionality extends the time before the disk need to be replaced or data remotely deleted.

The data structure in /dataX folders is following:

/data1
├── DFNEXT022
│   ├── 2018
│   │   ├── 01
│   │   │   ├── 2018-01-04_DFNEXT022_1515114584
│   │   │   ├── 2018-01-05_DFNEXT022_1515112201
                     ...
│   │   │   ├── 2018-01-30_DFNEXT022_1517353916
│   │   │   └── 2018-01-31_DFNEXT022_1517440320
│   │   ├── 02
│   │   │   ├── 2018-02-01_DFNEXT022_1517526718
│   │   │   ├── 2018-02-02_DFNEXT022_1517613118
│   │   │   ├── 2018-02-03_DFNEXT022_1517699520

Under normal conditions there is one folder with images per night - unless there is for example power cut or some other interruption during the night. We call these chunks of data "camera sessions".

As you can see, the data storage is organised by time and the folders have the date included in the name.

2018-01-30_DFNEXT022_1517353916 ... YYYY-MM-DD _ observatory name _ UNIX epoch time at the time when folder was created

Each of these folders contains up to over 1000 captured still images and a few other files like text logs. (The number of images depends of the duration of night and cloudiness.) The files (still images) have time-based file names as well, see the example

022_2018-01-31_143200_E_DSC_1644.NEF  ... NNN_YYYY-MM-DD_HHMMSS_T_DSC_XXXX.NEF

where

NNN1 is observatory serial number
YYYY-MM-DD_HHMMSS is UTC time of the beginning of the exposure
T is the camera type (missing or S: DFNSMALL, E: DFNEXT, K: DFNKIT)
DSC_XXXX.NEF is the original file name from the Nikon DSLR

There are also full-res lossy compressed jpeg files extracted from the NEF files, which are useful for quick check as it reduces data transfer volume and not everyone have NEF viewer or converter.

022_2018-01-31_143200_E_DSC_1644.thumb.jpg ... NNN_YYYY-MM-DD_HHMMSS_T_DSC_XXXX.thumb.jpg

And if not, it is easy to create a few with the following command

dcraw -e 022_2018-01-31_143200_E_DSC_1644.NEF

Note: If the removable disks get full, most of the NEF files will get automatically converted to .JPG.