SSAS - what could be a good starting point for memory settings?
Depending on how much RAM is on your server, below is a good starting point (given you have SSAS ONLY running on the server) :
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Refer to :SSAS Memory Configurations for Common Architectures and Analysis Services Memory Limits

SSAS uses memory limit settings to determine how it allocates and manages its internal memory.  Memory\LowMemoryLimit defaults to 65% of the total available physical memory on the machine (75% on AS2005), and Memory\TotalMemoryLimit (also sometimes called the High Memory Limit) defaults to 80%.  This is the total amount of memory that the SSAS process itself (msmdsrv.exe) can consume.
Once memory usage hits the Low limit, memory cleaner threads will kick in and start moving data out of memory in a relatively non-aggressive fashion.  If memory hits the Total limit, the cleaner goes into crisis mode… it spawns additional threads and gets much more aggressive about memory cleanup, and this can dramatically impact performance.