Hello, 

probably a lot of people have done this, now its my time. I wanted to test the 
performance of comstar over 8 GB FC. My Idea was to create a pool from a 
ramdisk, a thin provisioned zvol over it and so some benchmarks. 

However performance is worse then to the disk backend. So I measured the 
ramdisk performance on opensolaris (build 134):
--
a) OK whats the max we can do: 

r...@nexenta3:/volumes# dd if=/dev/zero of=/dev/null bs=8k
^C980922+0 records in
980922+0 records out
8035713024 bytes (8.0 GB) copied, 1.58065 seconds, 5.1 GB/s

Thats ok.

b) What can we do reqading from the ramdisk

r...@nexenta3:/volumes# dd if=/dev/ramdisk/ramdisk of=/dev/null bs=8k
^C297020+0 records in
297019+0 records out
2433179648 bytes (2.4 GB) copied, 2.79683 seconds, 870 MB/s

Looks ok

c) Ok what can we do writing to the ramdisk ? 

r...@nexenta3:/volumes# dd if=/dev/zero of=/dev/ramdisk/ramdisk bs=8k
^C71188+0 records in
71188+0 records out
583172096 bytes (583 MB) copied, 1.99645 seconds, 292 MB/s

Whats that ?? 300 MB to memory ? 

Any Tips why the ramdisk performance is so bad ? 

---

Regards, 
Robert
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