Questions about using gvirstor as a RAID0 solution

[Ivan Voras]

On 24/10/2011 11:21, carlopmart wrote:
> Hi all,
> 
>  I would like to use gvirstor as a thin provisioning solution for a
> mysql server, but I have some doubts about using it:

Yes, it's kind of what it was created for...

> a) Do I need to put "geom_virstor_load=YES"" on loader.conf or this
> kernel module is loaded automatically at boot If I create gvirstor
> volume using the label option??

You need to load the module yourself, the same as with other GEOM modules.

> b) Does gvirstor supports UFS journaling?? For example:
> 
>   gjournal label /dev/virstor/mydata
>   newfs -O 2 -J /dev/virstor/mydata

You can do that. It will be very inefficient (i.e. you will only avoid
fscks, there will probably be no performance gains at all) but nothing
should break. Both virstor and gjournal add their overheads
(specifically, they can be seek-intensive in different ways), so you
wouldn't want to use either if sustained random IO performance is important.

On the other hand, since you are using 9-stable, you can also use the
journaled soft-updates instead of gjournal, for much better efficiency.

> c) Can i use growfs utility If I need to expand a virstor volume at
> filesystem level??

Not exactly; virstor will immediately create a volume with large virtual
size (whatever you specify at the volume creation) ragardless of how
many physical devices you have. If you add more physical devices to the
virstor later, you do not have to do anything with the file system
itself, it will still see the original large virtual size.

If you are talking about expanding the virtual volume size, that's not
implemented yet (and in that case you would need to use growfs).

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