What is the test for review for abuse of discretion?

"[A] trial court's refusal or failure to dismiss or strike a prior conviction allegation under section 1385 is subject to review for abuse of discretion." (People v. Carmony (2004) 33 Cal.4th 367, 375.) "In reviewing for abuse of discretion, we are guided by two fundamental precepts. First, ' "[t]he burden is on the party attacking the sentence to clearly show that the sentencing decision was irrational or arbitrary. [Citation.] In the absence of such a showing, the trial court is presumed to have acted to achieve legitimate sentencing objectives, and its discretionary determination to impose a particular sentence will not be set aside on review." ' [Citations.] Second, a ' "decision will not be reversed merely because reasonable people might disagree. 'An appellate tribunal is neither authorized nor warranted in substituting its judgment for the judgment of the trial judge.' " ' [Citation.] Taken together, these precepts establish that a trial court does not abuse its discretion unless its decision is so irrational or arbitrary that no reasonable person could agree with it." (Id. at pp. 376-377.) Hence, " '[w]here the record demonstrates that the trial court balanced the relevant facts and reached an impartial decision in conformity with the spirit of the law, we shall affirm the trial court's ruling, even if we might have ruled differently in the first instance' " (Id. at p. 378.)

b. Sentencing.