The Storage Architecture That Saves $70,000 per Rack Without Sacrificing Performance
An all-NVMe storage array delivering 100 TB of usable capacity costs roughly $50,000 in drives alone. A tiered architecture delivering the same 100 TB costs roughly $18,000 in drives while delivering 85-90 percent of the performance for 95 percent of workloads. Across a five-rack deployment, that is $180,000 in total savings.
The Three Tiers
| Tier | Drive Type | Example Model | Quantity | Usable Capacity | Cost (Drives Only) |
|---|---|---|---|---|---|
| Tier 0: Cache | NVMe PCIe 4.0, 3 DWPD, 3.84تيرابايت | Samsung PM9A3 3.84TB | 4 (غارة 10) | 7.68 تيرابايت | $2,800 |
| Tier 1: Active Data | SAS SSD 12Gb/s, 3 DWPD, 3.84تيرابايت | Kingston DC1500M 3.84TB | 8 (غارة 10) | 15.36 تيرابايت | $5,600 |
| Tier 2: Bulk Capacity | SAS HDD 12Gb/s, 20تيرابايت | Toshiba MG10 20TB | 12 (غارة 6) | 160 TB usable | $4,800 |
| Total | 24 محركات | 183 TB usable | $13,200 | ||
Automated vs Manual Storage Tiering
Approach A: Automated Tiering (ZFS, Storage Spaces, vSAN). ZFS with a Special Allocation Class on NVMe, a primary pool on SAS SSDs, and a secondary pool on SAS HDDs. Hot blocks migrate to the fastest tier automatically based on access frequency. No manual management required.
Approach B: Manual Classification. The DBA places the database WAL on NVMe (Tier 0), data files on SAS SSD (Tier 1), and backups on SAS HDD (Tier 2). Better performance predictability, but requires ongoing manual management.
Server Configuration: A Tiered Storage Node
| عنصر | Selection | Reason |
|---|---|---|
| الخادم | Dell R760 (2يو, 24× 2.5 بوصة) | Sufficient bays for all three tiers |
| Alternative (higher density) | xFusion 2288H V7 (25× 2.5 بوصة, 28 NVME) | More NVMe bays for larger Tier 0 cache |
| وحدة المعالجة المركزية | 2x Xeon Gold 6448Y (32 النوى) | Filesystem operations. No GPU needed. |
| ذاكرة | 256 غيغابايت (16x 16 GB DDR5, 1DPC) | ZFS ARC: 128 GB for metadata and hot block caching |
| RAID/HBA | دقيقة H965i (16-port Gen5 tri-mode) | Single controller for NVMe, SAS SSD, and SAS HDD |
| Networking | 2x 25GbE SFP28 (front-end), 2x 100GbE (back-end) | 25GbE for client access, 100GbE for replication |
| نظام التشغيل | TrueNAS Scale or RHEL 9 with ZFS | ZFS for tiering. TrueNAS for appliance experience. |
Performance Estimates: 183 TB Tiered Storage
| Workload | Expected Performance | vs All-NVMe |
|---|---|---|
| 4K Random Read (Tier 0 cache) | ~850K IOPS, 80 us latency | 92 percent of all-NVMe |
| 4K Random Read (Tier 1 active data) | ~95K IOPS, 120 us latency | Consistent SAS SSD performance |
| 4K Random Read (Tier 2 cold data) | ~150 IOPS, 4ms latency | Sequential prefetch mitigates random penalty |
| Sequential Write (to NVMe cache) | ~3.5 GB/s (4x NVMe RAID 10) | Writes on NVMe, async destage to slower tiers |
Three Deployment Scenarios
1. VMware Datastore (50 VMs, mixed workloads). NVMe cache absorbs 80 percent of reads. SAS SSD handles active VMDKs. SAS HDD stores snapshots and templates. VMware admins experience NVMe-like latency with 60 percent lower storage cost.
2. PostgreSQL Database (2 تيرابايت, write-heavy OLTP). WAL on NVMe (Tier 0, mirrored). Data files on SAS SSD (غارة 10). Backups on SAS HDD (غارة 6). WAL writes at 2 GB/s sustained, data reads at 95K IOPS.
3. Media Post-Production NAS (50 TB active, 150 TB archive). Current projects on SAS SSD. Completed archives on SAS HDD. NVMe cache for metadata and small-file I/O.
Design Your Tiered Storage With Xincuan
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