[GE users] Initial findings with classic / BDB / RPC spooling over NFSv3 / NFSv4 on Linux

ccaamad m.c.dixon at leeds.ac.uk
Fri Jan 8 16:15:03 GMT 2010


I know I've only scratched the surface on this, but I thought I'd share 
some findings I've seen today when performing *simplistic* comparisons in 
job throughput on a RHEL 5.4 platform with spooling options suitable for a 
qmaster/shadowd install.

I've not accounted for all sorts of things, but I found it interesting and 
I hope others will also.


* Comments on Berkeley BDB spooling on a Linux NFSv4 share:

   I've not tried Kerberos authentication - only basic AUTH_SYS.

   Although it's not supported, no immediate SGE problems are noticeable,
   although I've not been seriously looking for them yet. However, I have
   noticed an interesting change vs. NFSv3 when having an HA NFSv4 server.
   If you perform a manual failover by the sequence of:

   1) Unconfigure the IP address on server
   2) Unexport filesystem on server
   3) umount filesystem on server
   4) mount filesystem on failover server
   5) Export filesystem on failover server
   6) Configure IP address on failover server

   A simple umount at step (3) doesn't work if a client had files
   open. Seems to eventually time-out: I need to take a closer
   look at this.


* Throughput: Submit a 10,000 job task array consisting of a job script
   with just the "echo" command, to execute on four 16-core servers:

   Run  Spool   NFS Execd   NFS server  qmaster Time  Jobs/second
        type    ver spool   load av.    (%cpu)  (sec)
   ===  ======= === ======= =========== ======= ===== ===========
    1   classic 3   shared    ~11           ?   1098      9
    2   bdb     4   shared    ~11          ~5%   486      21
    3   rpc/bdb 3   shared    ~11          ~3%   816      12

    4   classic 3   local     ~0.5        ~20%   427      23
    5   bdb     4   local     ~0.5         ~5%   418      24
    6   rpc/bdb 3   local     ~0.5         ~3%   625      16

   Only one result of each type was collected, so these figures are
   indicative only.

   Simple observations:

   1) Putting execd spool directories locally stops my NFS server and
      disks from being under strain.

   2) "qstat" and friends were very sluggish when qmaster was under strain.
      Using bdb in some form or other keeps my qmaster from being put under
      strain.


* Setup:

   NFS server   : SunFire X4150 2x 2.5GHz Harpertown, 16Gb/RAM, StorageTek
                  2530 disk array. RHEL5.4 x86_64.

   qmaster      : SunFire X4150 2x 2.5GHz Harpertown, 16Gb/RAM.
                  RHEL5.4 x86_64.

   execd servers: SunFire X4440 4x 2.7GHz Shanghai. CentOS 5.3 x86_64.

   "classic" - classic spooling, SGE_ROOT mounted NFSv3 by qmaster and
               execds

   "bdb"     - bdb spooling, SGE_ROOT mounted NFSv4 by qmaster, NFSv3 by
               execds

   "rpc/bdb" - bdb spooling, SGE_ROOT mounted NFSv3 by qmaster and execds,
               bdb spooling server running on NFS server.

   scheduler:
      schedule_interval 0:0:1
      flush_submit_sec      0
      flush_finish_sec      0


If you got to here, thanks for reading :)

Mark
-- 
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Mark Dixon                       Email    : m.c.dixon at leeds.ac.uk
HPC/Grid Systems Support         Tel (int): 35429
Information Systems Services     Tel (ext): +44(0)113 343 5429
University of Leeds, LS2 9JT, UK
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