GCS on grid control graph is high and write data slowly

Question

We writed more data to Oracle RAC 10.2 + ASM on Redhat.
It's slowly. When we check grap on Grid Control, we found high stat on "Global Cache Block Access Latency".
How can I tune or investigate?
###remark
Oracle Cluster 4 nodes (10.2 + ASM on redhat 4)
interconnect CAT 6 (1G) and use bonding

Answer 1

Just to be certain, how slow and which part of the Global Cache component:
AWR Report threshholds are (lower boundary - typical - upper boundary)
Avg time to process cr block request 0.1 - 1 - 10
Avg Global Cache cr block receive times 0.3 - 4 - 12
Avg time to process current block request 0.1 - 3 - 23
Avg Global cache current block receive time 0.3 - 8 - 30
You might be losing blocks? I have a link to this article...
http://www.dba-oracle.com/real_application_clusters_rac_grid/cache_stats.htm
I modified the query found at the link above for more nodes:
SELECT A.INST_ID "Node ID",
(select B.VALUE from GV$SYSSTAT B where B.inst_ID=A.INST_ID and B.NAME='gc blocks lost') "GC BLOCKS LOST",
(select C.VALUE from GV$SYSSTAT C where C.inst_ID=A.INST_ID and C.NAME='gc blocks corrupt') "GC BLOCKS CORRUPT"
FROM GV$SYSSTAT A
group by A.INST_ID
order by 1;
Each should come back zero or close to zero. If it doesn't then check with your Linux admins to tune to the interface settings. A tuning link is also in the above URL.