WD UltraSMR versus Seagate CMR enterprise procurement

Ultrastar HC690 vs Seagate Exos 32TB

Verified spec guide ·

WD Ultrastar HC690 32TB and Seagate Exos 32TB can land in the same procurement spreadsheet, but they should not be treated as equivalent 32TB enterprise drives. The architectural difference is the decision.

HC690 is WD UltraSMR/SMR for qualified SMR-aware stacks. The tracked Exos 32TB row is a Seagate enterprise CMR drive. That difference affects compatibility, workload fit and operational risk before price enters the conversation.

Left
WSH723220ALN6L4
Right
ST32000NM004K
Decision
Architecture first
Availability
Live rows below
Quick answer

Choose Seagate Exos 32TB for conventional enterprise storage that expects CMR behavior. Choose WD HC690 32TB only when the storage stack is already qualified for UltraSMR/host-managed SMR and density per rack is the primary goal. If the stack is not SMR-aware, Exos wins even if HC690 looks cheaper per raw TB.

Decision

Ultrastar HC690 32TB vs Exos 32TB: quick comparison

Use this as the procurement-level screen before looking at live price rows.

Decision pointArchitecture
Ultrastar HC690 32TBUltraSMR / host-managed SMR
Exos 32TBCMR in tracked Exos 32TB row
Decision pointCapacity
Ultrastar HC690 32TB32TB
Exos 32TB32TB
Decision pointInterface
Ultrastar HC690 32TBSATA and SAS variants
Exos 32TBSATA 6Gb/s in tracked row
Decision pointCache
Ultrastar HC690 32TB512MB
Exos 32TB512MB in tracked row
Decision pointBest workload
Ultrastar HC690 32TBSMR-aware object and retention tiers
Exos 32TBConventional enterprise storage
Decision pointAvoid for
Ultrastar HC690 32TBUnqualified RAID/NAS/random-write pools
Exos 32TBWorkloads requiring WD UltraSMR fleet standardization
Decision pointProcurement risk
Ultrastar HC690 32TBHost-stack compatibility
Exos 32TBExact Exos SKU/interface qualification
Decision pointDecision metric
Ultrastar HC690 32TBArchitecture first, price second
Exos 32TBCompatibility first, price second

Capacity impact by bay count

This shows the capacity delta only. The financial answer comes from the live $/TB rows on the page.

Drive count4 bays
Ultrastar HC690 32TB raw128TB
Exos 32TB raw128TB
Raw delta0TB
Drive count6 bays
Ultrastar HC690 32TB raw192TB
Exos 32TB raw192TB
Raw delta0TB
Drive count8 bays
Ultrastar HC690 32TB raw256TB
Exos 32TB raw256TB
Raw delta0TB
Drive count12 bays
Ultrastar HC690 32TB raw384TB
Exos 32TB raw384TB
Raw delta0TB
Current market status

No exact in-stock live row is currently matched for WSH723220ALN6L4 / ST32000NM004K. If no alternatives render, the model should be treated as unavailable in the tracked live catalogue.

Exact comparison rows ranked by current $/TB

Live prices · updated every 4-5 hours · last checked recently · exact-model rows only

Nothing in this tier is in stock right now. That is a stock statement, not a catalogue gap — see every channel we track.

Live acquisition math for exact comparison rows

This table is computed from live DatacenterDisk rows when an exact in-stock match exists. It is intentionally blank for unavailable models rather than filled with stale prices.

No exact in-stock row is available right now. Use the availability table for nearby live alternatives, then re-check the exact model before ordering.

The drives are not interchangeable

A 32TB label hides the most important distinction. HC690 obtains its density through WD UltraSMR. Exos 32TB in the tracked DatacenterDisk row is a conventional-recording enterprise Seagate drive. A normal storage stack can treat the latter as block storage in a way it should not assume for HC690.

That does not make HC690 inferior. It makes it specialized. In the right architecture, the denser SMR design can lower system-level cost. In the wrong one, it is a compatibility problem.

Rack density and power

Raw capacity is tied at 32TB per drive, but system economics can diverge. HC690 fleets may be built around SMR-aware write shaping and high density. Exos fleets may prioritize conventional behavior and broader plug-in compatibility.

Compare cost per protected TB, watts per protected TB and qualification cost. A drive-level idle watt figure is useful, but shelves, controllers, fans and rebuild time decide the final economics.

Which one to choose

Choose Exos for conventional enterprise servers, backup targets, ZFS pools, many Ceph deployments and environments where the storage stack has not been designed for zoned SMR behavior.

Choose HC690 for a data-center platform that already supports host-managed SMR and can turn density into fewer shelves or lower rack cost. The environment has to be known before the price comparison is meaningful.

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Frequently asked questions

Is HC690 equivalent to Exos 32TB?

No. HC690 is WD UltraSMR/SMR; the tracked Exos 32TB row is CMR. They need different compatibility checks.

Which is better for normal enterprise RAID?

The CMR Exos path is the safer default unless the RAID/storage platform explicitly supports HC690's SMR behavior.

Can HC690 have lower long-term cost?

Yes, but mainly in qualified SMR-aware fleets where density reduces shelves, power, rack units or operations cost.

Should I buy purely by the lowest price per TB?

No. Price per TB is the first screen, not the whole decision. Match recording method, interface, bay count, firmware support, warranty position and rebuild risk before accepting the cheapest row.

Sources

Specification claims on this page were checked against the pages below on 1 September 2026. Where a widely-repeated figure did not survive that check, we report what the source says now and say so in the text rather than repeating the familiar number.

  1. Western Digital - Ultrastar DC HC690 product page (WesternDigital.com, 2026)
    Used for: HC690 30TB/32TB model-number variants, SMR recording, SATA/SAS options, 550TB/year workload and 5-year warranty
  2. Western Digital - Ultrastar DC HC690 data sheet (WesternDigital.com, October 2024)
    Used for: WSH723200/WSH723220 model families, 30TB/32TB SMR, SATA 6Gb/s and SAS 12Gb/s, 512MB buffer, 7200 RPM, 260MB/s and 269MB/s maximum sustained transfer rates, power and sector-format notes
  3. Western Digital - SMR HDD technology for AI data centers (blog.WesternDigital.com, 2025)
    Used for: UltraSMR context, host-managed SMR stack requirements and suitable controlled-write workloads
  4. Zoned Storage - Shingled Magnetic Recording hard disks (ZonedStorage.io, 2026)
    Used for: sequential-write-required zones and ZBC/ZAC host-management behavior for host-managed SMR disks
  5. DatacenterDisk Research - Live price and stock database (DatacenterDisk.com, Live)
    Used for: current product availability, live prices, stock state, condition labels and cost-per-terabyte calculations