Should I use ""delaylog,nodatainlog,convosync=direct" with a CLARiiON CX3-80 LUN?

[Stuart Abramson_2]

Are there cases where this is recommended? Not recommended? Mostly I just use "plain" /etc/fstab entries.

[A. Clay Stephenson]

As usual, the answer is "it depends". For example, typically when using convosync=direct you also use mincache=direct. This has the effect of bypassing the buffer cache and makes sense when the application itself heavily caches that data (e.g. databases). For applications that actually need buffer cache, performance suffers greatly. The delaylog option is a good, all-around setting that gives up just a bit of reliability for better performance. Nodatainlog is another of those "it depends" but I generally set it. One of those you didn't mention is logiosize; it can have measurable impact upon performance.

You really have to test these options in your environment for your applications but a good place to start is "man_vxfs" and then ask more defined questions because your question as stated can only be answered "it depends". It even gets more tricky with arrays because with cache-centric arrays, you might be able to get by with convosync=direct,mincache=direct in situations that would otherwise need big (UNIX) buffer caches. One of the main advantages of these options which bypass buffer-cache is that it frees up memory for other things.

[whiteknight]

Hi Stuart,

It is all depands on your applications.
If you are using Oracle, I will recommend the above mount option.

Please refer :-
http://docs.hp.com/en/B3929-90011/ch05s04.html

the Whitepaper written by one of HP lab engineer
http://docs.hp.com/en/5576/JFS_Tuning.pdf


WK