[Lustre-discuss] lru_size very small

[Brock Palen]

Sorry for throwing up so many quick questions on the list in a short  
time.

Looking at the manual about locking,  the manual states

"The default value of LRU size is 100"

I looked on our login nodes to increase its value, currently lustre  
set lru_size to 32 for the MDS and 1 for 9 of the OST's, 3 for 1 OST,  
4 for 1 OST and 0 for 3 OST's.

I should note though that all 14 OST's are spread across two OSS,  
both with 16GB of ram (x4500's).

Compared to what the manual says this sounds really small.
Would this be a sign that we don't have enough memory in our OSS/ 
MDS's  for our number of clients?

I looked on a few of our clients, many only have 1 lru_size for the  
MDS and 0 for all the OST's.

Am I reading something wrong?  Or do we have to set this at start up,  
not let lustre figure it out from clients/ram  as stated in the manual.

This state worries me because it gives me the felling the cache will  
not function at all because of the lack of available locks.  I don't  
want to end up on the wrong end of "can speed up Lustre dramatically".

Thanks.

633 clients,
16 GB MDS/MGS
2x16GB OSS's.


Brock Palen
www.umich.edu/~brockp
Center for Advanced Computing
brockp at umich.edu
(734)936-1985