A typical 7200 rpm disk consumes about 5W when idle. For 24 drives, it's 120W. Rather substantial, but not an electric kettle level. At $0.25 / kWh, it's $0.72 / day, or about $22 / mo, or slightly more than $260 / year. But this is only the disks; the CPU + mobo can easily consume half as much on average, so it would be more like $30-35 / mo.
And if you have electricity at a lower price, the numbers change accordingly.
This is why my ancient NAS uses 5400 RPM disks, and a future upgrade could use even slower disks if these were available. The reading bandwidth is multiplied by the number of disks involved.
A typical 7200 rpm disk consumes about 5W when idle. For 24 drives, it's 120W. Rather substantial, but not an electric kettle level. At $0.25 / kWh, it's $0.72 / day, or about $22 / mo, or slightly more than $260 / year. But this is only the disks; the CPU + mobo can easily consume half as much on average, so it would be more like $30-35 / mo.
And if you have electricity at a lower price, the numbers change accordingly.
This is why my ancient NAS uses 5400 RPM disks, and a future upgrade could use even slower disks if these were available. The reading bandwidth is multiplied by the number of disks involved.