Network performance, RAID, load balancing and backups
In short: Performance and availability go together: RAID protects against disk failure, NIC teaming and load balancing remove single points of failure, and a sound backup scheme (full plus differential or incremental) means data can be restored after a disaster.
Measuring network performance
| Metric | What it tells you |
|---|---|
| Bandwidth | The maximum capacity of a link |
| Throughput | How much data actually gets through |
| Latency | How long data takes to travel from source to destination |
| Jitter | How much latency varies; critical for voice and video |
| Packet loss | The share of packets that never arrive |
| Availability | The percentage of time a service is up (for example 99.9%) |
RAID storage
RAID (redundant array of independent disks) combines disks to gain speed, redundancy or both. RAID is not a backup: deleting a file or a ransomware attack affects every disk at once.
- RAID 0 (striping): data is split across disks for speed and full capacity, but one failed disk loses everything.
- RAID 1 (mirroring): identical copies on two disks; if one fails the other carries on, and a replacement is rebuilt from it.
- RAID 5 (striping with parity): at least three disks; parity is spread across all of them, so any one disk can fail.
- RAID 6 (double parity): like RAID 5 with a second parity block, so two disks can fail at once.
- RAID 10 (mirroring + striping): at least four disks; mirrored pairs are striped for both speed and redundancy, at the cost of half the raw capacity.
Dual LAN (NIC teaming) and load balancing
NIC teaming joins two or more network cards in a server into one logical link, ideally cabled to different switches. If a card, cable or switch fails, traffic continues on the other, and in active-active mode both add bandwidth.
A load balancer spreads requests across several servers and runs health checks so failed servers stop receiving traffic. Common methods:
- Round robin: each new request goes to the next server in turn.
- Least connections: the server with the fewest active sessions gets the next one.
- Source IP hash: a client’s address always maps to the same server, keeping sessions together.
Asset management
You cannot protect what you do not know you have. Asset management keeps an up-to-date inventory of hardware, software and licences: owner, location, serial number, software version, warranty and support dates. It shows which devices need patching, which are out of support and which have gone missing.
Backup types
| Type | Backs up | Backup speed and space | To restore you need |
|---|---|---|---|
| Full | Everything | Slowest, largest | The one full backup |
| Differential | Changes since the last full | Grows each day | Last full + latest differential |
| Incremental | Changes since the last backup of any kind | Fastest, smallest | Last full + every incremental since |
The 3-2-1 rule: keep three copies of data, on two different types of media, with one copy off-site or offline. Test restores regularly.
Storage area networks (SAN)
A SAN is a dedicated high-speed network that connects servers to shared block storage. Servers see SAN storage as if it were a local disk. SANs run over Fibre Channel or over Ethernet with iSCSI, and they make it easier to replicate, snapshot and move data between servers and sites.
Practice
Which RAID level survives two simultaneous disk failures?
A full backup runs on Sunday and incrementals every other night. A disk dies on Thursday. What do you restore?
Why is RAID not a substitute for backup?
Key takeaways
- Measure bandwidth, throughput, latency, jitter, packet loss and availability.
- RAID 0 is speed only; RAID 1, 5, 6 and 10 add redundancy. RAID is not backup.
- NIC teaming and load balancing remove single points of failure.
- Differential restores need two sets; incremental restores need the whole chain.
- A SAN gives servers fast shared block storage.
Original content written by Mohamed Fayas for FM TecHub. © 2026 FM TecHub. You're welcome to share a link to this page; please don't copy the text elsewhere without permission.