This ticket is half request, half documentation bug report.

https://www.zabbix.com/documentation/2.2/doku.php?id=manual/config/items/itemtypes/zabbix_agent

The item documentation suggests that bps and bytes are valid options, which is not the case for Linux. The Linux agent only supports the other 4 options listed there. This should be documented.

However, this metric should be obtainable on Linux.

https://www.kernel.org/doc/Documentation/iostats.txt

Looking at the sar manpage, I found the following quote:

.bq bread/s – Total amount of data read from the devices in blocks per second. Blocks are equivalent to sectors with 2.4 kernels and newer and therefore have a size of 512 bytes. With older kernels, a block is of indeterminate size.