How to quickly fill a ZFS folder?

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brianmat

Weaksauce
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Sep 1, 2011
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As part of my performance testing of our new hardware I would like to build a 2 drive mirror and simulate a nearly full drive resliver to determine the time it would take to repair.

We'll be using ZFS mirrors to house all of our VMWare data but I am assuming on a striped mirror that wouldn't really matter that much (correct me if I am wrong).

I'm figuring a 2TB mirror would take way too long using /dev/urandom and I don't think using /dev/zero would help to find a worst case resliver.

Would using shred generate enough psuedorandom data to fill the drive? This will be run on OpenIndana for testing since we're doing an all-in-one with ESX and Napp-It.

I want to benchmark as much as I can while the system is under component testing as I can and this along with some bonnie++ numbers will give us something to go on moving forward and array rebuild time is a huge concern for me.
 
AFAIK, all zeroes is the only special case. You can fill with all 'A' or somesuch...
 
That's good to know. ZFS has so many behind the scenes features that I didn't want to make any assumptions as to setting up my test case.
 
Testing resilver speed is completely different with 1 file or 1 million files.
 
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