FSx for Windows File Server and Lustre file systems on SSD storage that could use HDD
What does ZopNight detect here?
ZopNight flags FSx for Windows File Server and FSx for Lustre file systems on SSD storage and prices a move to HDD from the storage capacity times the SSD-to-HDD rate gap. In us-east-1, Windows Multi-AZ storage lists at $0.230 per GB-month on SSD and $0.025 on HDD, so the gap is large when the workload tolerates HDD.
Signal and threshold
| Field | Value |
|---|---|
| Rule IDs | RC-195 |
| Category | rightsizing |
| Severity | low |
| Metric | none — pure configuration read |
| Threshold | storage type SSD on Windows or Lustre |
| Source | ZopNight |
| Permissions used | fsx:DescribeFileSystems |
Where it applies
SSD file storage costs several times HDD
The AWS price list for US East (N. Virginia) puts FSx for Windows File Server Multi-AZ storage at $0.230 per GB-month on SSD and $0.025 on HDD, and Single-AZ HDD at $0.013. A 10 TB Multi-AZ file share on SSD is about $2,300 a month for storage alone; on HDD, about $250.
AWS draws the line by workload. It describes HDD for home directories, user and departmental shares, and content management systems, and SSD for databases, media processing and data analytics. Plenty of plain file shares were created on SSD by default and never needed it.
Listing SSD file systems
aws fsx describe-file-systems \ --query 'FileSystems[?StorageType==`SSD`].[FileSystemId,FileSystemType,StorageCapacity,StorageType]' \ --output tableCheck FileSystemType: only WINDOWS and LUSTRE rows are candidates, since those are the FSx
types with an HDD option in the price list.
What ZopNight needs to price the change
- The storage type AWS reports is
SSD. - The file system type is Windows File Server or Lustre. OpenZFS and NetApp ONTAP file systems are skipped, because there is no HDD tier to move to.
- The provisioned storage capacity is known.
- SSD and HDD rates are known for the Region, and HDD is cheaper.
- A monthly cost is known for the file system, which caps the saving.
Why few file systems get a finding today
The fifth input is often missing. ZopNight’s monthly cost for an FSx file system is frequently unavailable, and without it the saving cannot be capped, so the rule stays silent rather than show an unbounded figure. The page describes the check as it runs when that cost is present. It never falls back to a fixed percentage.
The storage-rate gap on your capacity
saving = (SSD rate - HDD rate) per GB-hour x storage capacity in GB x 730capped at the file system's monthly costThroughput capacity and SSD IOPS are billed separately and are not part of this figure.
Moving a file system to HDD
- Check the file system’s IOPS and throughput in CloudWatch against HDD performance for its size.
- AWS does not allow changing a Windows file system from SSD to HDD in place. Take a backup:
aws fsx create-backup --file-system-id fs-0123456789abcdef0 - Restore it to a new file system configured with HDD storage:
aws fsx create-file-system-from-backup --backup-id backup-0123456789abcdef0 --storage-type HDD --subnet-ids subnet-0123456789abcdef0 - Move clients, DNS aliases and mount targets to the new file system, then delete the old one.