AZ-104 Part 2 — Storage

One storage account, four sub-services

Storage Account
├── Blobs   (files, images, backups)   <-- like AWS S3
├── Files   (SMB / NFS share)          <-- like a network drive
├── Queues  (small messages)
└── Tables  (cheap NoSQL k/v)

Replication — the exam's favourite trap

SKU	Copies	Where	Cost	When to pick
LRS	3	1 datacentre	💲 cheapest	Non-critical, cost-first
ZRS	3	3 zones in 1 region	💲💲	High-availability inside region
GRS	6	Primary + secondary region (no reads)	💲💲	Disaster recovery
RA-GRS	6	Same as GRS + read from DR	💲💲💲	DR + read-only from anywhere
GZRS / RA-GZRS	6	ZRS + secondary region	💲💲💲💲	Highest resilience

     LRS: [ dc-1  x3 ]
     ZRS: [ zone-1 | zone-2 | zone-3 ]
     GRS: [ primary  x3 ]  →  [ secondary x3 ]

Blob access tiers — pay for how often you touch data

Tier	Access pattern	Min retention
Hot	Reads/writes daily	none
Cool	Once a month	30 days
Archive	Rare, hours to rehydrate	180 days

Managed disks

• Standard HDD — cheapest, backups & dev.
• Standard SSD — most workloads.
• Premium SSD — production DBs.
• Ultra Disk — highest IOPS, data disks only.

Common commands

# Create account
az storage account create -n mystorage -g myrg -l eastus \
  --sku Standard_LRS --kind StorageV2

# Create a container and upload a file
az storage container create -n docs --account-name mystorage
az storage blob upload -c docs -f invoice.pdf -n invoice.pdf --account-name mystorage

# Generate a time-limited SAS link
az storage container generate-sas -n docs \
  --permissions rl --expiry 2026-12-31T00:00Z --account-name mystorage

Real-world example

A hospital keeps last-year MRIs in Cool, images older than 5 years in Archive (cheap), and today's scans in Hot for the doctors. A lifecycle rule auto-moves data between tiers → 60% cost saving without changing a single application.

Exam gotchas

• Soft delete is on by default in v2; recovers accidental blob deletes.
• Azure File Sync lets on-prem servers cache Azure File shares.
• SAS tokens = time-limited, permission-limited URL; safer than sharing keys.
• GRS = RA-GRS: only RA-GRS allows reads from the secondary region.