This article was machine-translated from French and is being reviewed. Prices are in Algerian dinars excl. VAT.
Preventive maintenance acts before failure, corrective maintenance after. Preventive reduces the likelihood of failures and bad surprises; corrective restores what has failed. They complement each other. The real question is the dosage, which depends on how much a downtime hour costs your activity.
In short
- Preventive maintenance: scheduled actions on the calendar, or triggered by monitored equipment status (alerts). Examples: updates, backup checks, cleaning, disk and UPS verification.
- Corrective maintenance: intervention after failure. It remains necessary, because no preventive eliminates all failures.
- The right dosage depends on your tolerance to downtime (clinic, pharmacy, retail or office), not a fixed ratio.
What is preventive maintenance?
Preventive takes two forms. The systématique form follows a schedule: one visit per month or quarter, regardless of equipment status. The conditionnelle form follows state: a disk space, temperature or disk health alert triggers intervention. A typical visit contains:
- Physical cleaning: dust in PCs and servers, clear rack ventilation. Dust and heat are common causes of office overheating.
- Updates: operating system, antivirus, browsers and firmware of routers, firewalls and NAS. Patches close known security holes.
- Backups: verify tasks ran, read logs, and restore a test file or database to prove the copy is usable. See the 3‑2‑1 backup rule.
- Hardware: disk health (SMART alerts, RAID status), free space, temperature, actual UPS battery autonomy.
- Security: unused accounts, access rights, default passwords, firewall status.
- Documentation: up‑to‑date inventory and written report of each visit.
The price depends on scope and frequency: it is set in the maintenance contract.
Advantage: a disk whose alerts signal degradation is replaced during a visit, not urgently. Limit: alerts do not warn of all failures. A disk can fail without warning. That is why backup remains essential.
What is corrective maintenance?
Corrective action follows an incident: the server won’t start, data is inaccessible, Wi‑Fi is cut. It usually follows the same steps: diagnosis, workaround to resume activity, repair or replacement, data restoration, then report with cause. It can be immediate (service stopped) or deferred (failure not blocking and intervention scheduled).
Corrective intervention costs consist of:
- Travel and intervention : on our confirmed quotes, this line appears in 27 orders, with a median of 4,500 DA HT and amounts from 1,500 to 18,000 DA HT (source: our quotes, median).
- Replacement hardware: price from the store in DA HT, see the computer shop.
- Business loss during downtime, which depends on your business and you alone can estimate.
All amounts in this guide are in DA HT.
The trap of corrective only: no visible expense until something breaks, but the first major failure occurs at a time you don’t choose. If backup was never tested, data may be lost. If the part is not in stock, downtime lasts until it arrives. For equipment critical to activity, keep a spare part (disk, power supply, switch).
Preventive vs. corrective comparison
| Criterion | Preventive | Corrective |
|---|---|---|
| Trigger | Schedule or supervision alert | Fault detected |
| Planning | Interventions scheduled in advance | Often urgent, depending on provider availability |
| Budget | Predictable (fixed price or scheduled visits) | Variable, depending on the fault |
| Backups | Controlled and restored to test | Often checked only after the incident |
| Updates | Programmed | Often postponed, creating open gaps |
| Stops | Planned, off‑peak hours | Unplanned |
| Limitations | Does not eliminate all faults | Repairs after the fact, does not reduce risk |
What mix for your SME?
If your activity poorly tolerates downtime (clinic, pharmacy, retail)
Strengthen preventive care: frequent visits, supervision with alerts, UPS, backups with written objectives (maximum data loss, maximum downtime) and tested restores, spare parts for critical equipment. Also keep a corrective plan with written response times. If activity depends on the Internet, consider a backup connection.
If your activity tolerates a few hours of downtime (services, office)
More spaced visits may suffice, provided the essentials are protected: tested backups, regular updates, UPS status. The rest can be handled on-demand corrective service.
If your fleet is recent and not critical
An on‑call corrective with minimal monitoring is possible: disk space, temperature and network connection alerts to warn before total failure. This choice becomes risky as the fleet ages or the activity depends more on it.
Traps to avoid
« We will do preventive later »: it is rarely urgent, so often postponed. Include it in the contract from the start, with a schedule and report.
« Updates can wait »: each patch closes known gaps. Conversely, an untested update may disrupt business software: test first on a pilot workstation and back up before.
"The UPS is optional": outages and voltage variations can damage disks and corrupt a database. The UPS allows a clean shutdown. For example, the EA265 Pro 650 VA UPS is listed at 10,500 DA HT (price on asloitech.com as of 06/11/2026, subject to availability). To size it, see UPS: how much power to choose.
« RAID is a backup »: no. RAID protects against disk failure, not deletion, ransomware or fire. See the guide on choosing between server and NAS.
Choosing the right contract
AsloTech offers IT maintenance contracts that can cover preventive, corrective or both, depending on your fleet. Also see the content of a maintenance contract. For equipment and rack organization, see organizing a network rack and our solution for professional IT hardware.
Frequently asked questions
Can we start with pure corrective and switch to preventive later?
Yes. The first step is an assessment: inventory, disk health, backups, overdue updates, UPSs, admin access. It often reveals weak points (dust, depleted UPS battery, never-restored backup) to address before starting the routine.
Does preventive maintenance prevent failures?
It reduces their probability and avoids surprises, but does not eliminate them. Power may fail without warning, a storm can damage equipment, human error can delete files. Backup and corrective maintenance remain necessary.
Does preventive maintenance include hardware renewal?
No. It maintains the existing equipment. See repair or replace a PC and renew the IT fleet to decide when to upgrade.
Should support be strengthened during a peak activity?
Yes, if a critical period is known (financial close, inventory, migration). Include exception cases and billing in the contract, and schedule a check before the period. Also see internal helpdesk.
Need an opinion on your site? A technician can come to assess your needs and advise you.