Four pieces of work, and what each one leaves behind
COOLORANGE SOLUTIONS LTD is an independent information technology consultancy working with small businesses across South Yorkshire from an office in Cudworth, Barnsley. Four kinds of engagement account for nearly everything the company is asked to do, and each one is described here by the document or the tested arrangement it leaves behind.
- Systems review. A written account of what is running, where it runs, who is able to reach it, and what would stop if any single part of it were switched off tomorrow morning.
- Migration planning. A plan document that names the order of moves, the rehearsal, the agreed cutover window and the rollback position, so that stopping remains a decision and not an emergency.
- Network and backup design. An addressing and equipment layout, a backup schedule written in plain hours, and a restore test carried out on a stated date with the result recorded either way.
- Documented handover. A network map, the location of the credential register, and operating notes written for whoever runs the system once the engagement has finished.
In practice the fourth item is the one clients remember, because it is the one they open a year later at half past seven in the morning.
Reviewing a system in the order that answers questions fastest
A review is not an inventory, and the difference matters: an inventory lists equipment, whereas a review explains what the business would lose if a given piece of it stopped. The order below is worked through in sequence, because each step narrows the next one.
- First What the business does on an ordinary Tuesday: which files are opened, which system takes the orders, and which task nobody is able to do while the network is down.
- Second Where the data actually lives, meaning the physical or hosted location of every set of records the business depends on, including the sets that live on one laptop.
- Third Identity and access: who holds an account, which accounts still belong to people who have left, and whether administrative rights are shared between several people.
- Fourth The network path from a desk to that data, including the router, the switch, the wireless access points and the internet circuit, with the speed of that circuit measured and not assumed.
- Fifth Backup and restore, which are two separate things, because a backup is a copy that was made and a restore is a copy that was proved to open.
- Sixth Licensing and support contracts, so that renewal dates and the party responsible for each system are written in one place.
Nearly every unreviewed network contains one switch that nobody present is able to account for, and it is usually the one carrying the accounts machine.
Planning a migration so that the rollback stays a decision
A migration is the move of a system from where it runs now to where it will run next, and the planning decides whether the move is dull. The plan names every move in order, the person who performs it, the check that confirms it worked, and the point at which the old arrangement is taken out of service. Nothing in it sits on a week grid, because a small business moves in the evenings and on the two Saturdays when the yard is quiet.
The rehearsal comes before the cutover. A rehearsal copies the data into the new system while the old one keeps running, so that the copy time is measured on the real circuit and the awkward files are found early. The cutover is the short window in which the business stops using one system and starts using the other, and it is agreed in hours, because that number governs every other number in the plan.
The rollback position is written down before the cutover begins: the condition under which the move is abandoned, and the state the old system must be left in so that abandoning it takes minutes. In practice a written rollback is almost never used, which is the argument for writing it, since the version held only in somebody's head is the version that fails at two in the morning.
Engagements are shaped around that structure and not around a fixed package. Some clients want the review and the plan, and will move the system themselves; others want the move performed and the notes handed over. The second costs more only because it takes longer.
Network and backup design, and the restore test that carries a date
Network design means deciding the addressing, the equipment and the layout on purpose instead of by accretion. Addressing is the scheme that gives each device its number on the network, and it is worth setting deliberately, because a scheme chosen once is readable by a stranger and a scheme grown over eight years is readable by nobody. Wireless coverage is planned from the shape of the building and the metal inside it, since a warehouse and an office of equal floor area need different numbers of access points.
Backup design starts from two figures the client supplies: how much work the business is willing to redo after a failure, and how long it is able to stand still while the system is rebuilt. The first sets how often copies are taken, and the second sets where they are kept, because a copy held offsite is safer and slower to bring back than a copy held in the building.
The restore test makes the rest of it true. On an agreed date a copy is taken from the backup, opened on separate equipment, and checked against something the client recognises, such as last month's invoices. The date, the file, the time the restore took and the outcome all go into the notes, whichever way the outcome went, which means the client owns a record of a restore that happened.
A backup nobody has ever restored is a filing habit, and it is a good one, but it is worth knowing which of the two you are paying for.
As found, as handed over
The two drawings below occupy one frame. Drag the handle, or use the slider beneath it, to wipe between a network as it is commonly found on a first visit and the same network once it has been documented. Both show the same six devices; only the knowledge of them differs.
As found As handed over
Working out the rate a cutover window demands
The window is agreed with the client first, and the rate has to follow from it. Enter the volume to be moved and the hours actually available, and the arithmetic below solves for the sustained transfer rate that window requires. Tick the read-back box when the data is to be read back and compared afterwards, because the same volume then crosses the link twice.
What is left with you
An engagement closes when the following four artefacts exist, are readable by somebody who was not present while the work was done, and are held by the client and not by the consultancy.
- The network map. The right-hand drawing above, produced for the client's own site: every device named, every address recorded and every link drawn as it physically runs.
- The location of the credential register. The register itself stays under the client's control; the notes state where it is, who holds it and which accounts it needs to contain.
- The backup schedule. What is copied, how often, where each copy is kept, and how long copies are retained before they are overwritten.
- The restore-test notes. The date of the test, the file that was opened, how long the restore took, and what the outcome was.
Those four documents are the point of the work. A client who holds them is able to instruct any competent engineer, including one who is not this company, which is a reasonable definition of a handover.