[THIN] Re: Alternative fileservers (EMC Celerra)

Many thanks for the reply.

  ----- Original Message ----- 
  From: Rick Mack 
  To: thin@xxxxxxxxxxxxx 
  Sent: Wednesday, March 26, 2008 12:12 PM
  Subject: [THIN] Re: Alternative fileservers (EMC Celerra)


  Hi Matt,

  I have an active pain avoidance mechanism so once I get burned with a product 
I tend to avoid it, and advise others to do the same. Sometimes that's unfair 
because a product has actually improved in the interim but you genarally only 
get one chance with me.

  The deal with the Celerra was that despite EMC protestations that it ws 
optimally tuned, whatever that means in a heterogeneous environment, we were 
seeing system pauses that just had to be network i/o related with consistently 
high redirector current commands on the TS systems.

  If you've got a windows based file server, the default values (set at the 
file server end)  are way too low for TS systems and will often result in TS 
pauses and even hangs. But you can tweak maxmpxct and maxworkitems on the file 
server to increase the resilience of the network i/o request mechanism and get 
rid of the hangs.

  Many NAS CIFS implementations use SAMBA or a derivative and with SAMBA you 
can tune the Max Mux value (equivalent to maxmpxct) to tailor it for a TS 
environment. But if the NAS implementation is a closed box then you've got a 
problem. Approaches to EMC about this issue didn't produce any results at the 
time so it was a choice of living with the pause issues or using something else.

  This may no longer be the case with EMC. Provided the Max Mux/(could also be 
MaxConnections) or MaxMPxCT equivalent may now be tunable so that everything 
will be fine. But if they aren't, then the Celerra remains as a possible bad 
choice for a busy TS environment, particularly if you're doing folder 
redirection and all that other fun stuff that increases network i/o requests.

  regards,

  Rick

  -- 
  Ulrich Mack
  Quest Software
  Provision Networks Division 

   
  On 3/26/08, M <mathras@xxxxxxxxxxxxxxxx> wrote: 
    Hello Rick,

    Can you elaborate on your interesting comment. 
    "The Celerra style NAS approach can have throughput problems in a TS 
environment. It's fine anywhere else"

    I am interested because we use this (it also cost a bomb so im told) and 
have had real issues with pausing Citrix sessions. Our Citrix team eventually 
pinpointed this to the way the disks were configured and the way departmental 
data was distributed.

    Matt

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