Good morning
I have an 2016 emon system (emonpi, 2xTX, emonth) with six years worth of data (100+ feeds) on the current SD card which is looking about full.
I have purchased a new preloaded SD from the shop and am in the process of thinking how best to transfer over (with a bit of much needed cleaning up along the way).
The system is used for monitoring and control of a completely off-grid property and has become somewhat indispensable. Historical data is important for decision making on a daily basis as well as a useful tool for monitoring the health of individual bits of the off-grid set-up.
I had imagined I would simply have to download csv data to date for reviewing and start the new card with no history. However the trim data feature that has appeared at some point suggests I could trim the data before back-up to something smaller (say 2-3 years) and transfer over. I have found no confirmation of whether this actually works ok other than a couple of queries a few years ago questioning it.
Can anyone confirm it does work for my purposes and is this a sensible way to proceed anyway?
Current system info below.
Server Information
Server Information
Services
-
emonhub :- Active Running
-
emoncms_mqtt :- Active Running
-
feedwriter :- Active Running - sleep 300s 3645 feed points pending write
-
service-runner :- Active Running
-
emonPiLCD :- Active Running
-
redis-server :- Active Running
-
mosquitto :- Active Running
-
demandshaper :- Active Running
-
emoncms_sync :- Active Running
Emoncms
- Version :- low-write 11.6.12
- Git :-
- URL :- GitHub - emoncms/emoncms: Web-app for processing, logging and visualising energy, temperature and other environmental data
- Branch :- * stable
- Describe :- 11.6.12
- Components :- Emoncms Core v11.6.12 | App v3.1.3 | EmonHub Config v2.1.5 | Dashboard v2.4.1 | Device v2.2.6 | Graph v2.2.4 | Network Setup v1.0.5 | WiFi v2.1.1 | Backup v2.3.4 | DemandShaper v2.2.3 | Postprocess v2.4.7 | Sync v3.2.0 | Usefulscripts v2.3.13 | EmonScripts v1.8.8 | RFM2Pi v1.4.2 | Emonhub v2.7.2 | EmonPi v3.0.3
Server
- CPU :- 1 Threads(s) | 4 Core(s) | 1 Sockets(s) | Cortex-A53 | 76.80MIPS |
- OS :- Linux 4.19.75-v7+
- Host :- emonpi | emonpi | (192.168.1.148)
- Date :- 2026-02-09 11:39:21 UTC
- Uptime :- 11:39:21 up 18:07, 0 users, load average: 0.39, 0.58, 0.54
Memory
- RAM :- Used: 22.51%
- Total :- 975.62 MB
- Used :- 219.66 MB
- Free :- 755.96 MB
- Swap :- Used: 0.00%
- Total :- 100 MB
- Used :- 0 B
- Free :- 100 MB
Disk
- **** :- - / :- Used: 54.10%
- Total :- 3.92 GB
- Used :- 2.12 GB
- Free :- 1.61 GB
- Read Load :- 723.44 B/s
- Write Load :- 1.37 KB/s
- Load Time :- 17 hours 59 mins
- /var/opt/emoncms :- Used: 98.48%
- Total :- 9.98 GB
- Used :- 9.83 GB
- Free :- 0 B
- Read Load :- 29.86 B/s
- Write Load :- 552.68 B/s
- Load Time :- 17 hours 59 mins
- /boot :- Used: 20.55%
- Total :- 252.05 MB
- Used :- 51.79 MB
- Free :- 200.26 MB
- Read Load :- 0 B/s
- Write Load :- 0 B/s
- Load Time :- 17 hours 59 mins
- /var/log :- Used: 25.50%
- Total :- 50 MB
- Used :- 12.75 MB
- Free :- 37.25 MB
- Read Load :- n/a
- Write Load :- n/a
- Load Time :- n/a
HTTP
- Server :- Apache/2.4.38 (Raspbian) HTTP/1.1 CGI/1.1 80
MySQL
- Version :- 5.5.5-10.3.17-MariaDB-0+deb10u1
- Host :- 127.0.0.1 (127.0.0.1)
- Date :- 2026-02-09 11:39:21 (UTC 00:00)
- Stats :- Uptime: 65241 Threads: 15 Questions: 81496 Slow queries: 0 Opens: 50 Flush tables: 1 Open tables: 44 Queries per second avg: 1.249
Redis
- Version :-
- Redis Server :- 5.0.3
- PHP Redis :- 5.0.2
- Host :- localhost:6379
- Size :- 1085 keys (1.27M)
- Uptime :- 0 days
MQTT Server
- Version :- Mosquitto 1.5.7
- Host :- localhost:1883 (127.0.0.1)
PHP
- Version :- 7.3.9-1~deb10u1 (Zend Version 3.3.9)
- Run user :- User: www-data Group: www-data video Script Owner: pi
- Modules :- apache2handlercalendar Core ctype curl date dom v20031129exif fileinfo filter ftp gd gettext hash iconv json v1.7.0libxml mbstring mosquitto v0.4.0mysqli mysqlnd vmysqlnd 5.0.12-dev - 20150407 - $Id: 7cc7cc96e675f6d72e5cf0f267f48e167c2abb23 $openssl pcre PDO pdo_mysql Phar posix readline redis v5.0.2Reflection session shmop SimpleXML sockets sodium SPL standard sysvmsg sysvsem sysvshm tokenizer wddx xml xmlreader xmlwriter xsl Zend OPcache zlib
Pi
- Model :- Raspberry Pi 3 Model B Rev 1.2 - 1GB (Sony UK)
- Serial num. :- 5B0A1802
- CPU Temperature :- 44.01°C
- GPU Temperature :- 44.0°C
- emonpiRelease :- emonSD-17Oct19
- File-system :- read-write
