Separate BIG LZ partition in or out of pool?

[koffie]

Hi,

First of all, thanks for creating greyhole. Excellent stuff, thanks for the time and efforts! It is much appreciated. We really can't say that often enough.

I just did a complete fresh install of 6.1 on a 500 GB disk and have separate root, swap, and /var/hda/files (LZ) partitions. The latter is rather big, 430 GB, maybe to be downsized later. I did that because I had read that for some the LZ is filling up quicker than it is being emptied by greyhole. I have two other 1TB drives in the pool. I think I understand the basic principles of greyhole, and I have mounted the shares locally. I am now slow-copying (10MB/sec) my back-up back to the HDA over the network, with my LZ staying "empty", and my 1TB disks filling up, as expected.

At the moment I have not added the LZ to the pool. I read somewhere that if you add the LZ partition to the pool, it speeds up the transfer. But I can't find anywhere a simple explanation of what the reason may be. Will this big LZ then also be used for storage with its own gh folder? Would this mean that my LZ is shrinking? That would mean that I would not have to downsize it with GParted. I was gonna create another partition from the 430 GB, to be added to the pool. But am I correct that this is not necessary if I just add the LZ to the pool?

Thanks in advance for your answer.
With kind regards
Koffie

[lrevxl]

The transfer would not significantly speed up by adding your LZ drive to the storage pool, even if your LZ happens to have the most amount of freespace, when Greyhole transfers a file from the LZ to a pool drive it's performing an rsync which copies the file, not a file move. (A file move from one directory to another would be instantaneous on the same drive -- a file copy can still take a long while.)

As to your other question, if you added your LZ to the pool, yes, it would begin to shrink, eventually. Once your two 1tb drives have < 430gb, your LZ partition would start to become a destination for files to be copied to from the LZ path.

In essence, you would not gain speed, you would gain space for your pool, and you would lose space for your LZ, make sense?

Many people put their LZ onto a storage pool drive simply to get it off their system drive, since potentially filling up your system drive can have negative consequences. The only downside to this approach that I can see is that it will potentially skew balancing a bit at the time of copying. The pool drive with the LZ on it will appear to have less freespace than it will have once the LZ is emptied. (i.e. say 20gb of files are in the LZ which are going to be moved off to various pool drives -- that space won't be used once the LZ is emptied, but at the time of choosing, the drive in question shows up with 20gb less free space). You don't have to worry about any of this since your LZ path is a partition of your system drive and is not part of your pool.

[koffie]

Thanks lrevxl, for being so clear and taking the time. It makes perfect sense.

Regards
Koffie