Re: [ldm-users] 20151028: 20151028: Pqact FILE writes with custom removal?

  • To: Tom Yoksas <yoksas@xxxxxxxx>
  • Subject: Re: [ldm-users] 20151028: 20151028: Pqact FILE writes with custom removal?
  • From: Donna Cote <d-cote@xxxxxxxx>
  • Date: Wed, 28 Oct 2015 15:22:56 -0500
Tom,

We moved our storage LDM system to zfs (on the storage disks, I don't think
the system filesystems changed) after experiencing problems with scour on
xfs.

When using xfs, we saw the load average regularly rise to 50, 60, once to
110 (15-minute average over all CPUs). Even after the job of removing a
day's worth of radar data (x days back) was moved to a bash script. The
scours would start stacking (per Karen's definition) and I even created a
bash script to kill all scour jobs every 3 hours.

Now, with zfs, the load average rarely rises above 6 and the amount of data
coming in just about equals the amount of old data we remove every day. The
scour jobs have not done any stacking.

Donna
The Academy
Texas A&M University


On Wed, Oct 28, 2015 at 11:20 AM, Tom Yoksas <yoksas@xxxxxxxx> wrote:

> Hi Mike,
>
> On 10/28/2015 10:02 AM, Michael Dross wrote:
>
>> Is there one type of filesystem that is more efficient at handling
>> these types file large volumes of finds/creations/deletions?
>>
>> ie. EXT4, zfs.
>>
>
> We (Unidata Program Center) have had good luck with ZFS on our
> Solaris 10 motherlode-class machines.
>
> It would be most interesting to hear other users experiences!
>
> Cheers,
>
> Tom
>
> On Oct 28, 2015, at 11:56 AM, Tom Yoksas <yoksas@xxxxxxxx> wrote:
>>>
>>> All,
>>>
>>> re: how to efficiently scour LDM-created data products from disk
>>>
>>> If one organizes one's data files into daily directories, the need to
>>> 'find' each file that should be scoured can be pared down to finding
>>> which directories+contents need to be scoured.  This does not, however,
>>> get around the fact that deleting large numbers of files
>>> (e.g., millions for NEXRAD Level III files kept on disk for long
>>> periods of time) is a _very_ costly endeavor.
>>>
>>> Cheers,
>>>
>>> Tom
>>>
>>> On 10/28/2015 09:47 AM, Gerry Creager - NOAA Affiliate wrote:
>>>> How often to you run your scour command? We've exercised scour pretty
>>>> hard and were able to watch it keep up, if it were run frequently.
>>>> There's a one-time penalty, if you've been running it, say, daily or
>>>> less frequently, but if you run it hourly, it should keep up.
>>>>
>>>> gerry
>>>>
>>>> On Wed, Oct 28, 2015 at 10:39 AM, Steve Emmerson <emmerson@xxxxxxxx
>>>> <mailto:emmerson@xxxxxxxx>> wrote:
>>>>
>>>>     LDMers,
>>>>
>>>>     On Wed, Oct 28, 2015 at 9:28 AM, Donna Cote <d-cote@xxxxxxxx
>>>>     <mailto:d-cote@xxxxxxxx>> wrote:
>>>>
>>>>         I would like to ask for a more io-friendly scour utility.
>>>>
>>>>
>>>>     It's on my list (see <https://github.com/Unidata/LDM/issues/27>.
>>>>     Can't say when I'll get around to it, though.
>>>>
>>>>     Regards,
>>>>     Steve Emmerson
>>>>
>>>>     _______________________________________________
>>>>     ldm-users mailing list
>>>>     ldm-users@xxxxxxxxxxxxxxxx <mailto:ldm-users@xxxxxxxxxxxxxxxx>
>>>>     For list information or to unsubscribe,  visit:
>>>>     http://www.unidata.ucar.edu/mailing_lists/
>>>> --
>>>> Gerry Creager
>>>> NSSL/CIMMS
>>>> 405.325.6371
>>>> ++++++++++++++++++++++
>>>> “Big whorls have little whorls,
>>>> That feed on their velocity;
>>>> And little whorls have lesser whorls,
>>>> And so on to viscosity.”
>>>> Lewis Fry Richardson (1881-1953)
>>>>
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>>>>
>>>
>>> --
>>> +----------------------------------------------------------------------+
>>> * Tom Yoksas                                      UCAR Unidata Program *
>>> * (303) 497-8642 (last resort)                           P.O. Box 3000 *
>>> * yoksas@xxxxxxxx                                    Boulder, CO 80307 *
>>> * Unidata WWW Service                     http://www.unidata.ucar.edu/ *
>>> +----------------------------------------------------------------------+
>>>
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>>
> --
> +----------------------------------------------------------------------+
> * Tom Yoksas                                      UCAR Unidata Program *
> * (303) 497-8642 (last resort)                           P.O. Box 3000 *
> * yoksas@xxxxxxxx                                    Boulder, CO 80307 *
> * Unidata WWW Service                     http://www.unidata.ucar.edu/ *
> +----------------------------------------------------------------------+
>
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