On Fri, Mar 5, 2010 at 7:41 AM, Abdullah Al-Dahlawi <dahl...@ieee.org>wrote:
> Hi Geovanni > > I was monitering the ssd cache using zpool iostat -v like you said. the > cache device within the pool was showing a persistent write IOPS during the > ten (1GB) file creation phase by the benchmark. > > The benchmark even gave an insufficient space and terminated which proves > that it was writing on the ssd cache (my HDD is 50GB free space) !!!!!!!! > The L2ARC cache is not accessible to end user applications. It's only used for reads that miss the ARC and it's managed internally by ZFS. I can't comment on the specifics of how ZFS evicts objects from ARC to L2ARC but that should never give you insufficient space errors. Your data is not getting stored in the cache device. The writes you see on the SSD device are ZFS moving objects from ARC to L2ARC. It has to write data there otherwise there is nothing to read back from later when a read() misses the ARC cache and checks L2ARC. I don't know what your OLTP benchmark does but my advice is to check if it's really writing files in the 'hdd' zpool mount point. -- Giovanni Tirloni sysdroid.com
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