SUMMARY When drive/mountpoint to monitor is in btrfs raid0, read and writes speeds are incorrect (seems to take only one of the drives in that raid) DETAILS: In my current case there's 2 drives in raid0 and plasma system Monitor reports half the speed. REPLICATE: -have 2 free devices/partitions (for ex: sda2 sdb2) -create the raid with them (mkfs.btrfs -L raid-test -d raid0 -m raid0 -f /dev/sda2 /dev/sdb2) -mount the raid (mount LABEL=raid-test /mountpoint) Monitor that mountpoint while doing read/writes (for write example: dd if=/dev/zero of=/mountpoint/GBfile bs=1M count=4096 oflag=nocache conv=fdatasync status=progress ) expected behaviour: the write (or read) speed should obviously be faster than a single drive behaviour: speed displayed is as if only one drive was used Operating System: KDE neon 5.26 KDE Plasma Version: 5.26.0 KDE Frameworks Version: 5.99.0 Qt Version: 5.15.7 Kernel Version: 5.15.0-52-generic (64-bit) Graphics Platform: X11 Processors: 12 × Intel® Core™ i7-3930K CPU @ 3.20GHz Memory: 62.7 GiB of RAM Graphics Processor: NVIDIA GeForce GTX 980/PCIe/SSE2
Can you confirm the real speed is higher than the one plasma-systemmonitor shows?
(In reply to David Redondo from comment #1) > Can you confirm the real speed is higher than the one plasma-systemmonitor > shows? Yes, the real speed is higher than the one plasma-systemmonitor shows. Running for example the dd command , plasma says at max around 490MB/s, dd around 900+ and gkrellm around 900+. Noticed something that could be related or a clue. Benchmarking with kdiskmark I used to have the same symptoms thaN plasma until I unchecked, in preferences, O_DIRECT.
Thanks