Treosulfan, Fludarabine Phosphate, and Total-Body Irradiation Before Donor Stem Cell Transplant in Treating Patients With High-Risk Acute Myeloid Leukemia, Myelodysplastic Syndrome, Acute Lymphoblastic Leukemia

Inclusion Criteria: * Acute myeloid leukemia (AML): * All AML patients beyond 1st remission; * Intermediate or high risk AML patients (based on South West Oncology Group \[SWOG\] cytogenetic criteria) in 1st complete remission * Myelodysplastic syndrome (MDS) * Other myeloid malignancies as chronic myelogenous leukemia (CML), CML accelerated phase, CML blast crisis, chronic myelomonocytic leukemia (CMML) (to be approved by patient care conference \[PCC\]) * With Karnofsky Index or Lansky Play-Performance Scale \> 70% on pre-transplant evaluation * Able to give informed consent (if \> 18 years), or with a legal guardian capable of giving informed consent (if \< 18 years) * Previous autologous or allogeneic HCT is allowed * Donors must be: * Human leukocyte antigen (HLA)-identical related donors or * Unrelated donors matched for HLA-A, B, C, DRB1, and DQB1 defined by high resolution deoxyribonucleic acid (DNA) typing or mismatched for one HLA allele, except for HLA-C where no mismatch is allowed * Able to undergo peripheral blood stem cell collection or bone marrow harvest * In good general health, with a Karnofsky or Lansky Play Performance score \> 90% * Able to give informed consent (if \> 18 years), or with a legal guardian capable of giving informed consent (if \< 18 years) * Acute lymphoblastic leukemia (ALL): all ALL patients not eligible for other protocols Exclusion Criteria: * Receiving umbilical cord blood * With impaired cardiac function as evidenced by ejection fraction \< 35% or cardiac insufficiency requiring treatment or symptomatic coronary artery disease * With impaired pulmonary function as evidenced by partial pressure of oxygen (pO2) \< 70 mm Hg and diffusing capacity of the lung for carbon monoxide (DLCO) \< 70% of predicted or pO2 \< 80 mm Hg and DLCO \< 60% of predicted; or receiving supplementary continuous oxygen * With impaired renal function as evidenced by creatinine-clearance \< 50% for age, weight, height or serum creatinine \> 2x upper normal limit or dialysis-dependent * With hepatic dysfunction as evidenced by total bilirubin or aspartate aminotransferase (AST) or alanine aminotransferase (ALT) \> 2.0 x upper normal limit or evidence of synthetic dysfunction or severe cirrhosis * With active infectious disease requiring deferral of conditioning, as recommended by an Infectious Disease specialist * With human immunodeficiency virus (HIV)-positivity or active infectious hepatitis because of possible risk of lethal infection when treated with immunosuppressive therapy * With central nervous system (CNS) leukemic involvement not clearing with intrathecal chemotherapy and/or cranial radiation prior to initiating conditioning (day -6) * With life expectancy severely limited by diseases other than malignancy * Women who are pregnant or lactating because of possible risk to the fetus or infant * With known hypersensitivity to treosulfan and/or fludarabine * Receiving another experimental drug within 4 weeks before initiation of conditioning (day -6) * Unable to give informed consent (if \> 18 years) or with a legal guardian (if \< 18 years) unable to give informed consent * Ineligible donors will be those: * Deemed unable to undergo marrow harvesting or PBSC mobilization and leukapheresis * Who are HIV-positive * With active infectious hepatitis * Females with a positive pregnancy test * Unable to give informed consent (if \> 18 years) or with a legal guardian (if \< 18 years) unable to give informed consent