by Serguey Shinder
In February 2023 we moved our three largest warehouses onto a new warehouse management system over a single weekend. The plan was careful. Stock would be counted on Friday night, loaded into the new system on Saturday, and checked against the old one before anything was switched over. If the numbers matched we would go live on Sunday morning, and if not we would try again a fortnight later. I was the person who would decide.
The reconciliation finished at ten to four on the Sunday morning. I had been up since eight on Saturday. It showed two hundred and twelve lines where the two systems disagreed, about one per cent of the total, and a note from the team that most of them looked like timing, goods booked in on Friday evening after the count. I read the note, agreed, and said go. I remember the relief. I also remember that I never opened the list.
Most of them were not timing. Eighty were stock sitting in the bay where we keep damaged goods waiting to go back to suppliers, which the new system had loaded as available to sell. Another forty had come across with no location at all. On Monday the branches sold cracked plasterboard and turned away orders for fixings that were on a shelf nobody could find. It took nine days to clean up.
Going over it afterwards, the decision was not the strange part. The strange part was how certain it had felt. After twenty hours awake, everything in me was pointed at one outcome, finishing, and the explanation that let me finish was the one I found most convincing. I did not weigh it against the list. I did not notice there was a list to weigh. Tiredness had not made me careless in any way I could feel. It had narrowed what I was looking at until the only thing left in view was the end.
And I was the worst person in the building to make that call. I had planned the migration, I wanted it to work, and I had been awake the longest.
Our cutovers are planned differently now. The conditions for going live are written down a week before, as numbers: no more than twenty unexplained differences, and none on a line that sold more than a pallet last month. The person who decides comes on shift at two in the morning, having slept, and has done none of the work. Anybody who has been on for more than twelve hours may advise and may not decide. And the decision is made by reading the differences, not a summary of them.
The next migration was delayed by a week at three in the morning, by a colleague who had gone to bed at ten. She was right, and I was too tired to have known it.
– Serguey Asael Shinder
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