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Beginner's Guide to Greyhole

tags greyhole storage pooling drive extender whs

Greyhole adds up the free space of all drives you choose to be in the pool.
It also enables as many copies of a single file as there are drives in the pool.
Files are distributed evenly throughout your drives with no manual action needed.
You will never have to worry about free space on single drives again, just the whole space of your pool matters.

If your HDA is already set up and running, skip to part 2.

Part 1 - Before installing Amahi

There are a few considerations before installing Amahi for use with Greyhole.

You can follow the Fedora 14 install guide, you will be all set up for Greyhole use.
The following is already considered in there, so you could skip to part 2 and won't be bothered by details.

Greyhole works through a so called Landing Zone (lz) for each share.
The lz is /var/hda/files/sharename.
Every file copied to a Greyhole storage pool will first go to the lz.
Greyhole will then move the file to one of the drives in the pool and create a symlinkfor it in the lz.
Every lz can be on a different drive, for this guide we put them all on the same drive and call them all together one lz.
The important thing about this is that you need to consider the size of the lz.
If you want to copy a large amount of data to the pool, the lz will fill up quickly before Greyhole can distribute the files.
It's best to choose the lz according to the planned use of the pool.

If you copy large amounts of data to the pool on a regular basis you need a big lz, so you had best give it it's own partition.
You should include the lz in the pool for this option, it will speed up transfers.
If you plan on fillíng up the pool little by little, you can leave the lz on the root partition and make the root partiton a bit bigger, say 30GB.
As the root partition must not go into he pool, the lz stays out of it in this scenario.
You should avoid a large root partition because the space can not be included in the pool and will be used only temporarily.
When installing Amahi, disconnect all drives but the OS drive. They will be added later.

To be able to use Greyhole, you have to turn on *Advanced settings* on your Amahi HDA.
Go to your dashboard, click on Setup, go to the Settings tab and check Advanced Settings.
Now go to the Shares tab and click on Storage Pool.
Check every disk you want to be part of the pool. Do not select the root partition.
Go back to the shares and check Uses pool for the shares you want to use it.
You can specify a number of extra copies for important files up to the number of disks you have in the pool.
Attention: this only protects against disk failures. If you delete a file, all copies are deleted, too.
Now you're all finished setting up Greyhole. As you copy files to the shares, Greyhole will take care of the rest.
Important: If you work with files on shares directly on the HDA, you have to Mount Shares Locally. You risk breaking the storage pool if you don't.

More about Greyhole can be found here: