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Typically, we use B4ms sized VM’s for up to 30 users. For more users either create additional VM’s and load balance, or just scale up to B8ms. If you only have 1 to 12 users, or it's a test machine, you might get away with a B2MSB2ms
"B" refers to the burst size. B machines are typically cheaper because Microsoft assume you're not using them 24x7.
"2" or "4 revers " refers to the number of cores - 2 core is 8GB, 4 cores is 16GB.
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