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Message ID: 350
Entry time: 26 Feb 2007
In reply to: 346
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| Author: |
Stefan Ritt |
| Topic: |
Info |
| Subject: |
RFC- support for writing to removable hard disk storage |
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In the MEG experiment, we simply installed 100TB of RAID disks and don't need to change anything 
But seriously, you are right that such a system might be beneficial. I propose to extend the current logger code to switch disks. In the current tr_start() funciton in mlogger, the code checks for "subdir_format" to create separate subdirectories like once per week. One could extend this code in the following way:
- Add an array of strings and name it "Path", such as
/dev/sda1/datadir/
/dev/sdb1/datadir/
- On each stop of the run, check if the current disk has enough space for one more run. Take either the "Byte limit" of that channel, or the actual size of the last run and multiply it by two or so. If the disk is "almost full", switch to the next array element in "Path". Append the file name, such as "/dev/sda1/datadir/run1234.mid" and put this into "Current filename" as a feedback for the user. Now write to the new disk/file.
- Add as string like "Execute on switch", which gets called after you switched to the next disk. This shell script can then handle the un-mounting of the full disk, notify the user etc. This is similar to the "/Programs/Execute on start run" in the ODB, but it gets only called if you switch the disk. |