[lustre-discuss] /proc/fs/lustre/llite/*/stats

[Faaland, Olaf P.]

Hi,

I have a couple of questions about these stats.  If these are documented somewhere, by all means point me to them.  What I found in the operations manual and on the web did not answer my questions.

What do

read_bytes                25673 samples [bytes] 1 3366225 145121869
write_bytes               13641 samples [bytes] 1 3366225 468230469

mean in more detail?  I understand that the last three values are MIN/MAX/SUM, and that their units are bytes, and that they reflect activity since the file system was mounted or since the stats were last cleared.  But more specifically:

samples:  Is this the number of requests issued to servers, e.g. RPC issued with opcode OST_READ?  

So if the user called read() 200 times on the same 1K file, which didn't ever change and remained cached by the lustre client, and all the data was fetched in a single RPC in the first place, then samples would be 1?  

And in that case, would the sum be 1K rather than 200K?

Thanks,

Olaf P. Faaland
Livermore Computing