the estimated hours to copy data from one fs to another?

[Hanry Zhou]

I know it depends on the data type and the disk type, but what is your very rough estimated rate on how much data you can copy from one file system to another in an hour?

Some data are oracle datafile, and the target disks are emc disk. Thanks,

[A. Clay Stephenson]

There are so many unknowns here that this is ludicrous. All I can say is assume that no more than 1/2 of your total i/o bandwidth will be realized (and that is optimistic). Your only meaningful data will be to start a copy and interrupt it after 10 minutes or so and extrapolate. Even then, your values may be skewed because of the ratio of large to small files copied during the sample interval may not reflect the total fileset's ratio and the load of the system and array at the two times might be very different.

[James R. Ferguson]

Hi Hanry:

This is going to be dependent on many factors. If you are moving across a network, then that's a very rate-limiting step. If this is disk-to-disk, your throughput is potentially the best. Beyond that, there are at least two things that may have the biggest impact on your timings:

1. The number of files in the filesystems. Given a constant overall size, more files will take longer to copy than just a few large ones. This is because there is more metadata overhead (inode creation and update).

2. Mount options for the receiving filesystem, particularly, will affect performance. For the fastest build, you might want to *temporarily* use the following on the destination filesystem:

# mount -F vxfs -o nolog,convosync=delay

See the manpages for 'mount_vxfs.

I suggest that you time a small fraction of what you ultimately intend to transfer and simply extrapolate to the larger sample size as an estimate of the time for *your* configuration.

Regards!

...JRF...

[Hanry Zhou]

Thanks for all your messsages.
I know there are a lot of elements, but just wanted to get an idea about the rate.