Suppose the village blacksmith needs to make ten swords for his jarl, how would he define the amount of iron he needs? Or when salting herring for the winter, was there a unit salt was measured in? What about nautical distances, or overland? Suppose I'm a Viking, and wanted to measure a length of rope. What would my base unit of length be?
For the iron, probably the smith would mention a number of finished raw material products. A common example is the osmund. It weighs about 350 grams and so the smith would say, I need a dozen osmunds, or some such. The osmund often looks like a big scone. There were also other earlier forms. One was like an omega with a small circle and heavy legs. Presumably it was carried on poles.
For precious metals they used the mark. It could differ in weight but was almost always around 210 grams. Presumably the mark was divided into, 1 mark = 8 öre = 24 örtugar = 192-384 penningar. This from Swedish coins. If we look at the earliest Swedish coins, we find that 192 times the actual weight of them, adds up to something like a mark.
If we look at balance weights for precious metals we find that there seems to be a common origin, and that is the Roman empire. For the Viking age weights the more immediate origin are weights from France and from the Caliphate. For one thing, the name of one of the weights, the öre, seems to have its name from the aureus.
For other things, like salt and food, it is difficult to find a proper measure. In medieval times they used different kind of pounds, but it is not certain that such a measurement existed around 900 ad.
From medieval tax laws we have other measurements from Sweden, and that is the bucket. It is quite possible that the bucket has an older origin, and that the Vikings used it. The tax values were often such that a farm would pay a bucket of butter, and a bucket pork.
For lengths they must have used ells for shorter measures. For travel on the sea there was the Veckosjö, the amount of rowing that a rower could do before needing rest. The Veckosjö was different depending on the circumstances. In general a Veckosjö was close to 8 kms, but in bad conditions, it could well be half of that.
But to get back to the ells, probably they would have used ells, or fathoms as a measurement, even though it is very difficult to find evidence for any of these, but that is what they did in ages from where we have evidence.