Jump to content

Why does appdata have to be on the cache disk?


CaptainTivo

Recommended Posts

I have finally switched over to version 6, a big improvement and lots of cool features.

I installed the mariadb docker and imported my Kodi database and it all works great.

One thing I don't like:  the appdata share in which all the persistent storage for dockers is on the cache disk and marked as "use cache disk: prefer".  This means that it is completely unprotected.  I would think that appdata should be protected.  On version 5, running mysql, I kept the databases on a regular share, parity-protected.  I have done a bit of searching and the recommendation seems to be that we should run a backup plugin to regularly save the appdata to a parity-protected share.  This seems clumsy.  My question is: why can't appdata be shared as cache "NO" or perhaps "YES"?  If we can, can I simply change the "Use cache disk" parameter to "NO" or must I re-create the appdata share on the protected disks?

Link to comment

You can put appdata on whichever disk you want.

Most people choose the cache drive for two main reasons.

1. Cache disks are typically SSD, so super quick comparatively. Heavy database access on an array drive is painfully slow in comparison.

2. If appdata is on an array disk(s), all disks involved plus the parity drive will stay spun up pretty much permanently.

Link to comment
15 minutes ago, jonathanm said:

You can put appdata on whichever disk you want.

Most people choose the cache drive for two main reasons.

1. Cache disks are typically SSD, so super quick comparatively. Heavy database access on an array drive is painfully slow in comparison.

2. If appdata is on an array disk(s), all disks involved plus the parity drive will stay spun up pretty much permanently.

OK, that makes sense.  I only have a regular 1 TB HDD as my cache disk, so the speed is not an issue.  I ran mysql under V5 with the database on a parity-share and did not notice any speed issues.  Is there any way to put *some* of the appdata directories on the parity-protected array?  If the mariadb databases directory was on a parity-protected disk, it probably would only be accessed during a database operation, right?

Link to comment
7 hours ago, CaptainTivo said:

 Is there any way to put *some* of the appdata directories on the parity-protected array?

Sure. It's not a typical scenario, so you have to do it somewhat manually. Move the folders where you want them, being sure not to muck up permissions. Then set the appdata share to cache:no, so the mover doesn't try to undo what you just did. Make sure all your dockers reference /mnt/user/appdata and not /mnt/diskX/appdata or /mnt/cache/appdata.

 

Many of the dockers will set permissions on their appdata folders differently from a normal share, so running new permissions or otherwise changing permissions and ownership of the appdata contents will likely break some dockers.

Link to comment

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...