## How are drives used for Erasure Code?

MinIO divides the drives you provide into erasure-coding sets of *2 to 16* drives.  Therefore, the number of drives you present must be a multiple of one of these numbers.  Each object is written to a single erasure-coding set.

        assertEquals(0x0010, response.getAttributes());
        // getLastWriteTime returns lastWriteTime (from readUTime) + serverTimeZoneOffset
        // readUTime multiplies the seconds value by 1000, and writeUTime divides milliseconds by 1000
        // So the round-trip should preserve the milliseconds value
        assertEquals(sampleTimeMillis + serverTimeZoneOffset, response.getLastWriteTime());
        assertEquals(1024, response.getSize());

- **MinIO creates erasure-coding sets of _2_ to _16_ drives per set.  The number of drives you provide in total must be a multiple of one of those numbers.**
- **MinIO chooses the largest EC set size which divides into the total number of drives or total number of nodes given - making sure to keep the uniform distribution i.e each node participates equal number of drives per set**.

   */
  public static <T extends @Nullable Object> Iterable<T> concat(
      Iterable<? extends Iterable<? extends T>> inputs) {
    return FluentIterable.concat(inputs);
  }

  /**
   * Divides an iterable into unmodifiable sublists of the given size (the final iterable may be
   * smaller). For example, partitioning an iterable containing {@code [a, b, c, d, e]} with a

   */
  public static <T extends @Nullable Object> Iterable<T> concat(
      Iterable<? extends Iterable<? extends T>> inputs) {
    return FluentIterable.concat(inputs);
  }

  /**
   * Divides an iterable into unmodifiable sublists of the given size (the final iterable may be
   * smaller). For example, partitioning an iterable containing {@code [a, b, c, d, e]} with a

      Iterator<? extends T>... inputs) {
    for (Iterator<? extends T> input : checkNotNull(inputs)) {
      checkNotNull(input);
    }
    return concat(consumingForArray(inputs));
  }

  /**
   * Divides an iterator into unmodifiable sublists of the given size (the final list may be
   * smaller). For example, partitioning an iterator containing {@code [a, b, c, d, e]} with a

     * int.
     */
    checkNonNegative("a", a);
    checkNonNegative("b", b);
    if (a == 0) {
      // 0 % b == 0, so b divides a, but the converse doesn't hold.
      // BigInteger.gcd is consistent with this decision.
      return b;
    } else if (b == 0) {
      return a; // similar logic
    }
    /*

        input.equals(".%2e", ignoreCase = true) ||
        input.equals("%2e%2e", ignoreCase = true)

    /**
     * Cuts this string up into alternating parameter names and values. This divides a query string
     * like `subject=math&easy&problem=5-2=3` into the list `["subject", "math", "easy", null,
     * "problem", "5-2=3"]`. Note that values may be null and may contain '=' characters.
     */