What is a defense attorney's obligation to advise defendants on issues in the plea context?

The People argue that a defense attorney's obligation to advise defendants on issues in the plea context is bound within a multitude of uncertainties, including what constitutes a "record of conviction," whether the prosecutor is able to augment available records to support allegations of prior convictions, and the possibility that the prosecutor may withdraw the plea bargain if a defendant challenges some aspects of the record, to the detriment of the defendant. We agree with this assessment, and note that in many cases, "strategic choices made after thorough investigation of law and facts relevant to plausible options are virtually unchallengeable; and strategic choices made after less than complete investigation are reasonable precisely to the extent that reasonable professional judgments support the limitations on investigation. In other words, counsel has a duty to make reasonable investigations or to make a reasonable decision that makes particular investigations unnecessary. In any ineffectiveness case, a particular decision not to investigate must be directly assessed for reasonableness in all the circumstances, applying a heavy measure of deference to counsel's judgments." (Strickland v. Washington, supra, 466 U.S. at pp. 690-691.) However, a court will not give deference to an attorney's strategic decision where "the failure of counsel to avail himself of information relevant to the defense removed all rational support from that decision." (In re Saunders (1970) 2 Cal.3d 1033, 1049.)