I will be using `scrypt` to store passwords in my application. As such, I'll be using SHA-256 and Salsa20 crypto primitives (with PBKDF2).

Having that in mind, how big salt should I use? 
Should it be equal to the size of SHA-256 output: 256bits or should it be equal to number of bits I'll take from this password stretching function: 512bits?

Considering that SSHA as used by OpenLDAP has only 32bit salt this seems fairly large...

In general: What is the rule of thumb for size of salt?

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Related:

http://security.stackexchange.com/questions/8015/what-should-be-used-as-a-salt

http://security.stackexchange.com/questions/8246/what-is-a-good-enough-salt-for-a-saltedhash