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PAM / PAM II, Flexscale, Flashcache

[ Edited ]

I thought Flexscale was needed to tune / enable PAM, however I am being told that Flexscale is legacy and I need Flashcache with PAM II?

Pls could someone explain the difference between these components?

Also, do the license options (flexscale or flashcache) come with the hardware or do they need to be purchased in addition to the card?

Re: PAM / PAM II, Flexscale, Flashcache

PAM or PAM I is the 1st generation hardware card to supplement read cache. 16GB.  Requres a Flexscale license.

PAM II or Flashcache is the 2nd generation hardware card to supplement read cache. 256\512GB.  Requires a PAMii license.

Both Certain tuning parameters can be set using system options using options flexscale.xxx

Re: PAM / PAM II, Flexscale, Flashcache

So flashcache and PAM II are the same things?

An IBM (N Series) disti is stating that Flexscale is no longer used, is this incorrect? 

Re: PAM / PAM II, Flexscale, Flashcache

Yes FlashCache and PAMII are the same thing.  It is due to technology used and marketing.

The FlexScale license is no longer used, but to tune PAMI or PAMII you still use the flexscale options.

The systems that support PAMI support PAMII, so stating the FlexScale is no longer used is mostly correct from a licensing and hardware perspective.

Please read the following for more information:

  • TR-3801 - Intro to PCS.pdf
  • TR-3832 - Flash Cache and PAM Best Practices Guide.pdf
  • TR-3842 - NetApp Flash Cache in Windows File Services Workloads.pdf
  • TR-3799 - The NetApp Performance Acceleration Module II in File Services Workloads

Re: PAM / PAM II, Flexscale, Flashcache

Great, thanks for your help.

Lastly, when you buy and install the hardware are the flexscale options available for configuration immediately?

Re: PAM / PAM II, Flexscale, Flashcache

Either shutdown the controllers or perform a cf takeover\giveback scenario and insert the PAM\FlashCache cards.

Install the license with license add XXXXXX

Configure Flexscale with:

  • flexscale.enable             on        (same value in local+partner recommended)
  • flexscale.lopri_blocks       off        (same value in local+partner recommended)
  • flexscale.normal_data_blocks on         (same value in local+partner recommended)
  • flexscale.pcs_high_res       off        (same value in local+partner recommended)
  • flexscale.pcs_size           0GB        (same value in local+partner recommended)

Let it sit for a few days and then evaluate your working set size during peak or daytime usage:

stats show -p flexscale-access –i 1 –n 100

This is where you might need some help.  You will need to review the current usage, cache hit and cache misses over the period of time and determine if the working set of the data is too great for the currently installed PAM card.  If it is then you back the normal data blocks to off, otherwise leave it as is.  Odds are that leaving normal data blocks on will be fine.  It is highly unlikely that you will need to enable lopri blocks.

Re: PAM / PAM II, Flexscale, Flashcache

Thanks again