ZFS L2arc 16.0E size

[Frank de Bot (lists)]

Frank de Bot (lists) wrote:
> Hello,
> 
> I have a FreeBSD 10.1 system with a raidz2 zfs configuration with 2ssd's
> for l2arc . It is running '10.1-STABLE FreeBSD 10.1-STABLE #0 r278805'
> Currently I'm running tests before it can go to production, but I have
> the following issue. After a while the l2arc devices indicate 16.0E free
> space and it starts 'consuming' more than it can hold
> 

I've tried to 'debug' with dtrace, I found out different things:

- l2arc_write_buffers sometimes caused the vdev->vdev_stat.vs_alloc to
grow larger than vdev->vdev_asize.
- l2arc_dev->l2ad_end is larger than vdev->vdev_asize
- At some point l2arc_eviction isn't doing anything, but
l2ard_dev->l2ad_evict is higher than l2ard_dev->l2ad_hand . taddr is
matching l2ard_dev->l2ad_evict . I would assume it should evict that
space. l2arc_write_buffers will continue because there seems te be room
enough, I guess this would be caused by vdev_asize - vs_alloc is
negative and indicating a 16.0E freespace.

It could be that I'm assuming wrong things or interpret things wrong.
Please let me know.


Frank de Bot