[lustre-discuss] Lustre and Elasticsearch

[John Bent]

How does the lock manager avoid disk IO?  Locks don’t survive MDS0 failure?

> On Nov 26, 2017, at 8:29 PM, Dilger, Andreas <andreas.dilger at intel.com> wrote:
> 
> The flock functionality only affects applications that are actually using it. It does not add any overhead for applications that do not use flock. 
> 
> There are two flock options:
> 
>  - localflock, which only keeps locking on the local client node and is sufficient for applications that only run on a single node
> - flock, which adds locking between applications on different clients mounted with this option. This is if you have a distributed application that is running on multiple clients that controls its file access via flock (e.g. Producer/consumer). 
> 
> The overhead itself depends on how much the application is actually using flock. The lock manager is on MDS0, and uses Lustre RPCs (which can run at 100k/s or higher), and does not involve any disk IO. 
> 
> Cheers, Andreas
> 
> On Nov 26, 2017, at 12:03, E.S. Rosenberg <esr+lustre at mail.hebrew.edu> wrote:
> 
>> Hi Torsten,
>> Thanks that worked!
>> 
>> Do you or anyone on the list know if/how flock affects Lustre performance? 
>> 
>> Thanks again,
>> Eli
>> 
>>> On Tue, Nov 21, 2017 at 9:18 AM, Torsten Harenberg <torsten.harenberg at cern.ch> wrote:
>>> Hi Eli,
>>> 
>>> Am 21.11.17 um 01:26 schrieb E.S. Rosenberg:
>>> > So I was wondering would this issue be solved by Lustre bindings for
>>> > Java or is this a way of locking that isn't supported by Lustre?
>>> 
>>> I know nothing about Elastic Search, but have you tried to mount Lustre
>>> with "flock" in the mount options?
>>> 
>>> Cheers
>>> 
>>>  Torsten
>>> 
>>> --
>>> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
>>> <>                                                              <>
>>> <> Dr. Torsten Harenberg     Torsten.Harenberg at cern.ch          <>
>>> <> Bergische Universitaet                                       <>
>>> <> Fakutät 4 - Physik        Tel.: +49 (0)202 439-3521          <>
>>> <> Gaussstr. 20              Fax : +49 (0)202 439-2811          <>
>>> <> 42097 Wuppertal           @CERN: Bat. 1-1-049                <>
>>> <>                                                              <>
>>> <><><><><><><>< Of course it runs NetBSD http://www.netbsd.org ><>
>> 
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