# Monitoring

## diskio

IOPS: Input/Output Per Second. 每秒输入输出量，也叫TPS.

```
SELECT non_negative_derivative(mean(reads),1s) as "read" FROM "diskio"
SELECT non_negative_derivative(mean(writes),1s) as "write" FROM "diskio"
```

throughput:

```
SELECT non_negative_derivative(mean(read_bytes),1s) as "read" FROM "diskio"
SELECT non_negative_derivative(mean(write_bytes),1s) as "write" FROM "diskio"
```

Utilization:

```
SELECT non_negative_derivative(last("io_time"),1ms)
FROM "diskio"
WHERE "name" =~ /^(v|s|)d(a|b|c|d)$/
GROUP BY "host","name",time(_interval)
```

Queue length:

```
SELECT non_negative_derivative(last("weighted_io_time",1ms))
FROM "diskio"
WHERE "name" =~ /^(v|s|)d(a|b|c|d)$/
GROUP BY "host","name",time(_interval)
```