How do I combine several small HDDs to make one large HDD?

[justme2]

Many thanks btsnpcs - very useful information.
The only reservation I have now, after reading the links you gave, is that if one of the drives (within the larger spanned drive) fails, then you risk losing all the data - a significant consideration !
Therefore, bearing this in mind,  the spanned drive would need to be backed-up frequently to mitigate against such data loss occurring ...

Many thanks again - much appreciated.

If a single high capacity HDD fails, the same situation applies - possibility of loss of all data! The question is, is one or more of three spanned drives any more likely to fail than a single drive? Whatever the system, backup is essential but then the backup device may fail. What then? I used CDR/DVR in the past but after storage some became unreadable.

My objection to spanned drives would be the increased noise and power requirements and my strategy would be to convert each drive to USB and use independently.