Re: Sluggish performance on head r311648

On Wed, 2017-01-11 at 00:02 -0500, Ultima wrote:
> I'v been noticing lately sluggish performance, maybe zfs? First
> noticed
> this a few days ago right after upgrading on Jan 7th to r311648 and
> the
> last upgrade before that was around dec 30-jan 1 (not sure of rev).
> Decided
> to upgrade again today. I usually build and install head every week
> or two,
> but I have been extremely busy the past couple months.
> 
> FreeBSD U1 12.0-CURRENT FreeBSD 12.0-CURRENT #16 r311903: Tue Jan 10
> 17:20:11 EST 2017 amd64
> 
> Normally when one of my services scans a few directories it takes
> about 15
> seconds tops, it has been taking several minutes. I want to note that
> this
> service is running inside a jail with vnet enabled. Also the
> directory it
> scans is a nullfs to a dataset. This is just one of the many side
> effects
> i'v been noticing, another is extremely slow reads with bhyve+zvol.
> Starting to wonder if it maybe hardware related.
> 
> I decided to check commits log before posting and not much has
> happened to
> zfs recently other than, Add missed vfs.zfs.zfetch.max_idistance in
> r309833, and 309714 which doesn't really look related (could be
> wrong). But
> these were committed about a month ago so that is not likely the
> case.
> 
> 
> Anyone else experiences similar results as of recent?
> 
> 
> Sorry for being noise if this is hardware related.

One thing I keep a look out for, is in gstat, if one drive is busier
than the others, it's a clear sign of a drive dying. Offlining and
replacing the drive usually makes a huge difference.

Also, in all of these cases, SMART data shows no sign of problem and no
errors in 'zpool status'. Just watch and see if any of the drives is
working harder than the others has been the surest way to troubleshoot
performance issues, in my experience.

/K

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