[Lustre-discuss] Performance Issue with lustre 2.0

[Alexey Lyashkov]

Gianluca,

if you don't have plan to use mix of 1.8 and 2.0 clients, you can apply small patch, which should be reduce MDS traffic.

diff --git a/lustre/llite/dcache.c b/lustre/llite/dcache.c                                               
index 22a929d..b133956 100644                                                                            
--- a/lustre/llite/dcache.c                                                                              
+++ b/lustre/llite/dcache.c                                                                              
@@ -427,9 +427,6 @@ int ll_revalidate_it(struct dentry *de, int lookup_flags,                            
         ll_frob_intent(&it, &lookup_it);                                                                
         LASSERT(it);                                                                                    
                                                                                                         
-        if (it->it_op == IT_LOOKUP && !(de->d_flags & DCACHE_LUSTRE_INVALID))                           
-                GOTO(out_sa, rc = 1);                                                                   
-                                                                                                        
         ll_prepare_mdc_op_data(&op_data, parent, de->d_inode,                                           
                                de->d_name.name, de->d_name.len, 0, NULL);                               
                                                                                                         
that patch add more cache on client side, but have some interop issue in mixed env, which need to be fixed on MDS side.



On Nov 19, 2010, at 14:15, Gianluca Tresoldi wrote:

> Hi everyone,
> 
> I'm testing lustre 2.0 in a pre-production environment and I encountered some problems.
> 
> My test environment consists of:
> 1 MDS/MGS (not combined) with 48G of ram and 16 xeon E5520 core
> 1 OSS with the same characteristics.
> 1 Client 
> Both MDS and OSS are connected to an ISCSI shared storage with different volumes.
> 
> I've also production environment with lustre 1.8.2 and 2 filesystem served by:
> 2 MDS/MGS where each server is active for one file system and passive for other.
> 2 OSS: Same configuration of MDS.
> 50 Client that runs apache web-server.
> 
> I've performed a 8 hours stress test in both environment using apache log's for replicate real traffic, this is the results:
> 
> Lustre 1.8.2
> Avg load: on Mds 0,8 on Oss 0,2 and  network load on mds (on gigabit NIC dedicated to lustre traffic) about 50.000 Kb/s.
> 
> Lustre 2.0.0
> Avg load: on Mds 2,8 on Oss 0,1 and  network load on mds (on gigabit NIC dedicated to lustre traffic) about 180.000 Kb/s.
> 
> On lustre 2.0 the network traffic is much higher than on Lustre 1.8.2, if we considered that in addition to the stress test, on Lustre 1.8.2, also production runs, i think there is a problem.
> 
> With TCPDump I saw that when I run multiple "ls -l" on Client connected to lustre 1.8.2 only some time client send packet to MDS, with client connected to lustre 2.0 all the time.
> 
> I Think that client 2.0 doesn' t cache files' attr.
> 
> 
> could someone help me?
> Thanks in advice and have a very nice day. ;)
> 
> P.S.
> Sorry for my not perfect English.
> 
> -- 
> Gianluca Tresoldi
> ***SysAdmin***
> ***Demon's Trainer***
> Tuttogratis Italia Spa
> E-mail: gianluca.tresoldi at tuttogratis.com
> http://www.tuttogratis.it
> Tel Centralino 02-57313101
> Tel Diretto 02-57313136
> <linux40.jpg>Be open...
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