Cache pool full, but why ?

[vlaugier]

Hi,

 

when I look at the my cache pool from here :

 

I feel like my cache pool should have 514 Gb free and usable. Unfortunately, whenever I try to push new files to any share that's set up to use cache (only, prefer or yes), I meet "disk full" errors.

 

Obviously it seems the first SSD, the 1tb is full and the second is untouched. But it's not clear in the gui that the second one cannot be used.

I would like to be able to use this space.

Also I think unraid is "confused" too because if a "cache-yes" or "cache-prefer" share met a full cache, they should push data directly to the array, instead of raising errors, right ?

 

 

I'm not sure if it's related or not, but I feel like my share are a bit confusing when I take a look at the free space  of each share :

 

How come a lot of the Cache-Only shares have very different free space ? 

Diagnostics attached

 

 

 

sunraid1-diagnostics-20200507-1716.zip

[trurl]

On mobile now so can't look at Diagnostics, but you probably have raid1 mirror (the default) for cache pool so total capacity is only equal to the smaller disk. 

 

In order for a user share to overflow, cache must have less than Minimum Free.

 

I'm sure others will respond but I will check back. 

[John_M]

Your cache pool is actually configured as RAID0 but trurl's point still applies. If you want to use the full capacity of your un-matched SSDs you'll need to re-balance to SINGLE mode.

 

As to why the capacity reported is wrong, well, that's a feature of btrfs. Some would call it a bug but it's been like that for a long time and I imagine it would be relatively easy to fix.

[vlaugier]

30 minutes ago, trurl said:

On mobile now so can't look at Diagnostics, but you probably have raid1 mirror (the default) for cache pool so total capacity is only equal to the smaller disk. 

 

In order for a user share to overflow, cache must have less than Minimum Free.

 

I'm sure others will respond but I will check back. 

Thank you,

 

actually, I remember switching to RAID0 and the capacity is the largest SSD (1TB).

 

 

It's a bit confusing because, while at the btrfs configuration lvl, it seems the capacity seems to be 1Tb (consistent with the behavior), at the Main GUI lvl, the capacity seems to be 1.5tb. Also, as I was saying, it seems like the Shares themselves behave like the capacity is 1.5tb.

[vlaugier]

Just now, John_M said:

Your cache pool is actually configured as RAID0 but trurl's point still applies. If you want to use the full capacity of your un-matched SSDs you'll need to re-balance to SINGLE mode.

 

As to why the capacity reported is wrong, well, that's a feature of btrfs. Some would call it a bug but it's been like that for a long time and I imagine it would be relatively easy to fix.

Thank you a lot.

If I do that, am I going to lose data on the cache disks ?

[John_M]

1 minute ago, vlaugier said:

If I do that, am I going to lose data on the cache disks ?

You shouldn't, but there's always the possibility of something going wrong.

[vlaugier]

As a future reference for people encountering this particular scenario, I had to free a bit of space on the first full disk before being able to effectively be able to rebalance into single mode