Hi All,
I'm attempting to determine how much compression to run, where is the balance between disk speed, data size and CPU bottlenecking on my particular hardware. Fortunately I have a ton of data which will eventually migrate to this FreeNAS machine and I can use this data as a representative sample for how compressible things will be.
My question is, if I go into View Volumes => Edit ZFS options I can change the compression level. When does this take effect? Is it immediate for new data written to the dataset? Does the dataset then have some data compressed with different compression schemes? Or does it re-compress everything that's already there?
A related question: Is there a way to see how hard the CPU is having to work? While rsyncing data over from another machine, if I run top, SSHD is running 25% of the cpu (this is a 2x dual core machine....so is ssh maxing out 1 core?). Below that is rsync taking about 7% and nothing significant below that... That is with maximum gzip compression turned on (the data is being funneled through what I think is a gigabit switch, but it could be 100mbps).
ps, I copied a folder from an existing machine. On the original (linux) machine du -hs shows 1.4GB. On the freeNas box with lzjb compression it shows 1.6GB and with maximum gzip it's 1.5GB. As far as I know the original filesystem isn't compressed, and presumably even if it were it wouldn't be better than gzip -9 would it? Why is the data getting bigger?
Any thoughts/advice much appreciated!
I'm attempting to determine how much compression to run, where is the balance between disk speed, data size and CPU bottlenecking on my particular hardware. Fortunately I have a ton of data which will eventually migrate to this FreeNAS machine and I can use this data as a representative sample for how compressible things will be.
My question is, if I go into View Volumes => Edit ZFS options I can change the compression level. When does this take effect? Is it immediate for new data written to the dataset? Does the dataset then have some data compressed with different compression schemes? Or does it re-compress everything that's already there?
A related question: Is there a way to see how hard the CPU is having to work? While rsyncing data over from another machine, if I run top, SSHD is running 25% of the cpu (this is a 2x dual core machine....so is ssh maxing out 1 core?). Below that is rsync taking about 7% and nothing significant below that... That is with maximum gzip compression turned on (the data is being funneled through what I think is a gigabit switch, but it could be 100mbps).
ps, I copied a folder from an existing machine. On the original (linux) machine du -hs shows 1.4GB. On the freeNas box with lzjb compression it shows 1.6GB and with maximum gzip it's 1.5GB. As far as I know the original filesystem isn't compressed, and presumably even if it were it wouldn't be better than gzip -9 would it? Why is the data getting bigger?
Any thoughts/advice much appreciated!