Thanks Peter,
On Apr 26, 2011, at 2:16 PM, Peter Tribble wrote:
> On Mon, Apr 25, 2011 at 11:58 PM, Richard Elling
> <richard.ell...@nexenta.com> wrote:
>> Hi ZFSers,
>> I've been working on merging the Joyent arcstat enhancements with some of my
>> own
>> and am now to the point where it is time to broaden the requirements
>> gathering. The result
>> is to be merged into the illumos tree.
>>
>> arcstat is a perl script to show the value of ARC kstats as they change over
>> time. This is
>> similar to the ideas behind mpstat, iostat, vmstat, and friends.
>>
>> The current usage is:
>>
>> Usage: arcstat [-hvx] [-f fields] [-o file] [interval [count]]
>>
>> Field definitions are as follows:
>
> [Lots of 'em.]
>
>> Some questions for the community:
>> 1. Should there be flag compatibility with vmstat, iostat, mpstat, and
>> friends?
>
> Beyond interval and count, I'm not sure there's much in the way of
> commonality.
> Perhaps copy -T for timestamping.
The Joyent code (and the original, IIRC) had a "time" field. I've added a
"date"
field, too. However, in both cases the format is fixed. I'd rather make that
localized
in some meaningful manner, more like the "-T d" options.
>
>> 2. What is missing?
>>
>> 3. Is it ok if the man page explains the meanings of each field, even though
>> it
>> might be many pages long?
>
> Definitely. Unless the meaning of each field is documented elsewhere.
They are floating around the blogosphere, but yes, there is great value in
documenting them in a meaningful manner.
>
>> 4. Is there a common subset of columns that are regularly used that would
>> justify
>> a shortcut option? Or do we even need shortcuts? (eg -x)
>
> If I was a user of such a tool, I wouldn't know where to start. Which
> fields ought
> I to be looking at? There are a whole bunch of them. What I would expect is a
> handful of standard reports (maybe one showing the sizes, one showing the ARC
> efficiency, another one for L2ARC).
The ones I usually find interesting are the hit rates and usage. There are many
posts in this forum were people ask about how much RAM is needed for L2ARC,
metadata, etc. Measurements are better than models.
How about a separation in the form:
rates (hits,misses,...)
rate% (%hits,%misses,...)
sizes (c,p,l2size,...)
l2arc (l2*)
>
>> 5. Who wants to help with this little project?
>
> I'm definitely interested in emulating arcstat in jkstat. OK, I have
> an old version,
> but it's pretty much out of date and I need to refresh it.
Good idea :-)
-- richard
--
Richard Elling
rich...@nexenta.com +1-760-896-4422
Nexenta European User Conference, Amsterdam, May 20
www.nexenta.com/corp/european-user-conference-2011
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