RunInfo.xml FlowcellLayout section meaning of FlowcellSide

Question

[b10hazard]

In the Illuminas RunInfo.xml file there is a flowcell layout section that looks like this:

<FlowcellLayout LaneCount="2" SurfaceCount="2" SwathCount="2" TileCount="78" FlowcellSide="1">
    <TileSet TileNamingConvention="FourDigit">
        <Tiles>
        <Tile>1_2101</Tile>
        <Tile>1_2102</Tile>
        <Tile>1_2103</Tile>
        <Tile>1_2104</Tile>

Question #1

I know the meaning of LaneCount, SurfaceCount, SwathCount, and TileCount, but I don't know what FlowcellSide means. Can anyone explain what FlowcellSide means?

Question #2

I also noticed that the tile numbers in this XML only use SurfaceCount 2, SurfaceCount 1 is never used. For example, the tile number is supposed to be in the following format Lane_SurfaceSwathTile. However, there is never a tile like 1_1101, but there is 1_2101. Why isn't Surface 1 ever shown in the tile numbers?

Answer 1

[GenoMax]

FlowCellSide indicates physical position where the flowcell ran. HiSeq/NovaSeq can run two flowcells simultaneously.

Position A = FlowcellSide 1
Position B = FlowcellSide 2.

However, there is never a tile like 1_1101, but there is 1_2101. Why isn't Surface 1 ever shown in the tile numbers

That is because the flowcell you are looking at is of SP type. This NovaSeq flowcell is the lowest yield (currently) and is imaged only on bottom surface. Other types of flowcells will have those numbers.