Linux/DiskSpeedPerformance
- How to check and analize disk to find slow disk issues
iostat
- %util – Percentage of elapsed time during which I/O requests were issued to the device.
- r_await, w_await – The average time (in milliseconds) for read / write requests issued to the device to be served.
install
apt install sysstat
run iostat
iostat -x 1 3
- the numbers after the -x(extended) is 1 - delay, and 3 -repeat
ps aux
browse processes waiting for I/O, use watch to monitor processes with STAT flag 'D' like below:
watch -n 1 "(ps aux | awk '\$8 ~ /D/ { print \$0 }')"
Basic disk operations
See mounted disk e.g. sda
mount | grep "/dev/sd"
scsi details - e.g. to map how they are mounted from cloud provider
$ sudo lsscsi
Azure
find disks
az vm show -g myResourceGroup -n myVM --query "storageProfile.dataDisks"
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