Some links on this page are affiliate links: if you buy through them we may earn a commission, at no extra cost to you.
Direct answer: VM storage should be sized for capacity, performance, availability, growth and total cost—not just for the number of gigabytes assigned to a virtual disk. Treat storage as a layered system: guest filesystem → partition or LVM → virtual disk → datastore or cloud volume → physical or provider storage. Expanding one layer does not automatically expand the others.
Use thin provisioning only when physical capacity, snapshots, growth and overcommitment are continuously monitored. When extending to the cloud, first decide whether you need backup, disaster recovery, temporary bursting, a VMware-compatible environment, native cloud migration or simple file/object-storage offload. Each has different latency, networking, resilience, licensing and cost implications.
Start with the workload, not the VM template
There is no universal storage allocation formula for a virtual machine. Requirements depend on the application, current usage, growth, recovery objectives, availability design and the behavior of other workloads sharing the storage system.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Before creating or resizing a virtual disk, collect:
#1 Best Overall
- Get NVMe solid state performance with up to 1050MB/s read and 1000MB/s write speeds in a portable, high-capacity drive(1) (Based on internal testing; performance may be lower depending on host device & other factors. 1MB=1,000,000 bytes.)
- Up to 3-meter drop protection and IP65 water and dust resistance mean this tough drive can take a beating(3) (Previously rated for 2-meter drop protection and IP55 rating. Now qualified for the higher, stated specs.)
- Use the handy carabiner loop to secure it to your belt loop or backpack for extra peace of mind.
- Help keep private content private with the included password protection featuring 256‐bit AES hardware encryption.(3)
- Easily manage files and automatically free up space with the SanDisk Memory Zone app.(5). Non-Operating Temperature -20°C to 85°C
- Guest-used capacity and current virtual-disk size
- Monthly, annual, seasonal and short-term growth
- Average and peak IOPS, throughput, read/write ratio and latency
- Database data, logs, checkpoints and temporary-file behavior
- Snapshot, backup, replication and migration requirements
- Recovery-point objective (RPO) and recovery-time objective (RTO)
- Site, availability-zone and regional failure requirements
- Encryption, compliance and key-management requirements
- Expected migration and ongoing replication traffic
- Capacity, performance, backup, replication and network-transfer costs
A useful capacity worksheet should distinguish guest-used space, virtual-disk capacity, actual datastore consumption, snapshot space, backup staging, growth reserve and failure reserve. Do not apply a universal “keep 20% free” rule without considering the platform’s rebuild behavior, replication scheme, snapshots, maintenance procedures and workload volatility.
The original discussion of VM storage correctly emphasizes that sizing depends on the scope of virtualization, business growth, application behavior and future users or services, rather than on a fixed VM specification. The underlying storage-pool risk remains relevant.
Capacity is not performance
A large disk is not necessarily a fast disk. Measure and design separately for:
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
- IOPS: important for databases, virtualization metadata and transaction-heavy applications
- Throughput: important for backups, analytics, media and large sequential transfers
- Latency: often more important than peak throughput for transactional systems
- Burst behavior: short spikes can exhaust credits or queues even when averages look safe
- Queue depth and contention: several VMs can compete for the same controllers, datastore or storage tier
Deduplication, compression, cache, RAID or erasure coding and replication can change both effective capacity and performance. A small database-log disk may need lower latency and more sustained write performance than a much larger archive disk. Conversely, paying for premium IOPS on an infrequently accessed file or archive workload may provide little value.
Some cloud services make performance an explicit allocation rather than a side effect of capacity. For example, Google Cloud describes Hyperdisk designs in which IOPS and throughput can be provisioned independently of capacity. See the Google Cloud storage architecture guidance for the applicable service limitations.
Understand the storage layers
When an administrator says “the disk is 1 TB,” that may refer to several different values:
| Layer | What it means |
|---|---|
| Guest-used space | Data currently consumed inside the operating system |
| Filesystem | The structure that presents usable space to applications |
| Partition or LVM | The guest boundary containing the filesystem |
| Virtual disk | The capacity presented by the hypervisor or cloud control plane |
| Datastore or cloud volume | The resource storing the virtual disk |
| Physical or provider storage | The underlying disks, pool, replication system and billing model |
A thin-provisioned 1-TB virtual disk may initially consume much less than 1 TB in the datastore. However, the datastore must be able to accommodate it as data grows. Free space reported inside the guest is not the same as physical free space below the VM.
Thick versus thin provisioning
| Model | Benefits | Risks and trade-offs |
|---|---|---|
| Thick | Predictable capacity accounting, lower overcommitment risk and simpler operational controls | Oversized disks strand capacity and commit resources before the guest needs them |
| Thin | Better initial utilization, faster allocation of large logical disks and flexibility for uncertain growth | Concurrent growth, snapshots, clones or replication can exhaust the underlying pool and affect many VMs |
When thick provisioning is appropriate
- Storage overcommitment is unacceptable
- Capacity and performance must be deterministic
- Workloads are stable and well understood
- The platform or application vendor prefers reserved capacity
- The organization has sufficient physical capacity and prioritizes predictability
When thin provisioning is appropriate
- VM sizes are difficult to predict or utilization is uneven
- The team monitors physical free space and projected growth
- There are enforceable quotas, alerts and an emergency expansion plan
- Snapshots and clones are short-lived and governed
- Disk expansion and backend reclamation have been tested
Thin provisioning changes when capacity is consumed; it does not remove the eventual capacity requirement. Monitor absolute physical free space, provisioned-to-physical overcommitment, guest usage, snapshot growth, latency, IOPS, throughput, replication journals and the reserve required for rebuilds and maintenance.
Rank #2
- Solid state performance with up to 800MB/s read speeds in a portable drive. (Based on internal testing; performance may be lower depending on host device, interface, usage conditions and other factors. 1MB=1,000,000 bytes.)
- Back up your content and memories on a storage solution that fits seamlessly into your mobile lifestyle.
- Take it with you on your adventures—up to two-meter drop protection means this durable drive can take a beating. (Based on internal testing.)
- Secure it to your belt loop or backpack for extra peace of mind thanks to the tough rubber hook.
- From Sandisk, a brand professional photographers trust to take on assignments.
Place VM disks according to behavior
Separating disks can make performance, backup and recovery easier to manage, although it is not automatically beneficial on every platform. Common categories include:
- Operating-system disk
- Application binaries
- Database data
- Database and transaction logs
- Temporary or scratch data
- User profiles and shared files
- Backup repositories and staging space
- Archive data
Use storage policies or tiers based on measured behavior rather than labels alone. Logs generally have a write-latency requirement; archives generally prioritize capacity and price. Also account for noisy neighbors: a backup, rebuild or analytics job can degrade unrelated VMs sharing the same datastore or controller.
In VMware environments, datastores, datastore clusters, storage policies and Storage DRS can help place or rebalance workloads, but exact menus, automation and licensing vary by vSphere release, vCenter version, datastore type and whether the environment uses VMFS, NFS, vSAN or another storage platform. Verify the procedure in the documentation for the deployed release.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsMonitor before you expand
Expansion should be planned before an outage, not started when a datastore is already full. Track:
- Physical free capacity and the rate at which it is declining
- Logical capacity promised to VMs compared with physical capacity
- Guest-used capacity and the largest growth contributors
- Snapshot age, size and chain depth
- Datastore or volume latency, IOPS, throughput and queue depth
- Deduplication and compression efficiency
- Replication lag and journal consumption
- Space needed for rebuilds, failover, backups and migration copies
Set alerts according to the time required to buy, provision, migrate or fail over storage. A fixed percentage is less useful than a threshold that leaves enough time to respond. Use both absolute-capacity alerts and projected-growth alerts.
Expand storage safely: the layered procedure
- Confirm a current backup and a tested recovery path.
- Identify the exact disk, controller, volume and guest device. Do not rely only on device names if several disks look similar.
- Check snapshots, replication, maximum-size limits, partition-table type and application support.
- Increase the virtual disk or cloud volume in the hypervisor or provider control plane.
- Rescan the disk inside the guest operating system.
- Extend the partition, LVM logical volume or other guest container if required.
- Extend the filesystem using the operating system’s supported procedure.
- Verify the result from inside the guest and in the backend storage system.
- Check application health, latency and capacity consumption after the change.
- Update documentation, monitoring and the next capacity forecast.
Azure’s documentation makes this distinction explicit: resize the managed disk first, then expand the guest volume. The same layered principle applies to VMware, AWS and Google Cloud.
VMware virtual disks
Broadly, VMware can extend a virtual hard disk while the VM is powered on, but the guest partition and filesystem still need separate expansion. AWS’s VMware operations guidance also describes extending VMware virtual hard disks while powered on.
Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minutePC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Before changing a disk, check its virtual-disk type, snapshots, replication state, maximum supported size and guest partition layout. Broadcom warns that increasing a virtual disk does not resize the partition automatically; the guest may see unallocated space at the end of the disk. Restrictions can apply when snapshots exist or when the disk type is unsupported. Consult the applicable Broadcom procedure for the vSphere release and disk format.
Rank #3
- Capacity Display Variance: 500GB external ssd often appears as around 465GB on Windows. MacOS can show full 500 GB capacity. This is binary calculation difference and doesn’t affect SSD hard drive actual physical storage
- 1050 MB/s Speed: Instantly access to your files with blazing-fast 10Gbps external SSD read up to 1050MB/s and write up to 1000MB/s. LED Light indicates USB SSD instant activity
- Data Security: Solid state drives S.M.A.R.T. health diagnostics and adaptive TRIM optimizing data block management ensures consistent write speeds and extends the longevity of the portable SSD
- USB-C & USB-A Cable: Both cables featuring rapid USB 3.2 Gen2, this USB SSD effortlessly bridges devices, enabling seamless cross-platform file transfers and backup between computers, smartphones, tablets and iPhone
- Always Fast: No slowdowns for large file transfers. With SLC caching (25% of current available capacity allocated as high-speed cache), this external SSD delivers steady 10Gbps for transfers within the cache capacity
Azure managed disks
For a Windows VM, the current Azure portal workflow is generally:
- Open the VM.
- Stop and deallocate it if the selected disk type or VM generation requires this.
- Select Disks, then select the disk.
- Select Size + performance.
- Choose a larger size and select Resize.
- Inside Windows, extend the volume in Disk Management or with an appropriate supported command.
Azure does not support shrinking an existing disk in place. Azure documents a 4,095-GiB maximum for OS disks, while MBR partitioning can restrict usable capacity to 2 TiB. A larger disk may therefore require GPT or separate data disks. Disk type, VM generation and operating-system support determine whether expansion can occur without deallocation. See the Windows expansion documentation.
For Linux, resize the managed disk, identify the correct device, expand the partition, then grow the filesystem. Depending on the filesystem, that may involve tools such as xfs_growfs or resize2fs. Verify with lsblk, df -h and filesystem-specific commands. Azure documents different online-expansion conditions for Premium SSD v2, Ultra Disk, Standard HDD, Standard SSD and Premium SSD; check the Linux procedure before scheduling the change.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →AWS EBS volumes
With EBS Elastic Volumes, supported EC2 instances can generally increase volume size, change volume type and adjust provisioned performance without detaching the volume or restarting the instance. The operation itself is not separately charged, but the new configuration is billed once modification starts.
After the EBS modification, separately expand the partition and filesystem inside the instance. Check instance support, modification limits, operation timing and boot-volume partition-table restrictions. EBS volumes cannot normally be shrunk in place; AWS recommends creating a smaller volume and migrating the data when reduction is required. See the EBS modification documentation.
Google Cloud Persistent Disk and Hyperdisk
Google Compute Engine offers several storage categories, including Persistent Disk and Hyperdisk. Hyperdisk can make capacity, IOPS and throughput separate design decisions, which is useful for workloads whose performance requirement does not scale directly with gigabytes.
As with other platforms, increasing a cloud volume is only the control-plane step. Rescan the device and expand the guest partition, logical volume and filesystem as appropriate. Confirm current limits, supported online-resize behavior and pricing in the relevant Google Cloud disk documentation. Provider prices vary by region, disk type, provisioned performance and billing changes; do not treat an isolated pricing example as a universal quote.
Recommended Free Tools
What “extend to the cloud” can mean
Cloud extension is an architectural choice, not simply the addition of a remote datastore.
Rank #4
- Easily store and access 2TB to content on the go with the Seagate Portable Drive, a USB external hard drive
- Designed to work with Windows or Mac computers, this external hard drive makes backup a snap just drag and drop
- To get set up, connect the portable hard drive to a computer for automatic recognition no software required
- This USB drive provides plug and play simplicity with the included 18 inch USB 3.0 cable
- The available storage capacity may vary.
1. Cloud backup
Object storage or a managed backup service can provide off-site retention, ransomware recovery and compliance archives. It is not automatically a low-latency VM datastore. Large restores are limited by network bandwidth, provider throttling, deduplication efficiency and the recovery design.
2. Disaster recovery
Replicate VM data or images to a cloud recovery environment. Test RPO and RTO under normal and degraded network conditions, including DNS, identity, routing, dependency ordering, licensing, cloud capacity, failover traffic, egress and failback. A recovery plan that copies data but cannot boot the required application stack is incomplete.
3. Cloud bursting or temporary capacity
Bursting can help with short-lived demand, but the application must tolerate WAN latency and have a practical way to access identity, databases, files and security services. Validate the whole application path, not just storage throughput.
Free tools Windows power users keep installed
One-click scans. No signup required.
4. VMware-compatible cloud extension
Azure VMware Solution runs VMware Cloud Foundation components on dedicated Azure infrastructure and is designed to preserve familiar VMware operations. VMware Cloud on AWS similarly combines VMware management and virtualization with AWS infrastructure. These approaches can simplify migration, extension and recovery when compatibility and speed matter more than redesign.
The trade-off is cost and continued dependence on the VMware operating model. Budget for managed VMware service capacity, storage, backup, connectivity, supporting Azure or AWS resources and possible egress. Review current commercial terms directly; product packaging and licensing change.
5. Native cloud VM migration
A converted workload may use Azure Managed Disks, Amazon EBS, Google Persistent Disk or Hyperdisk, cloud file services and object storage for backups and archives. Native cloud designs can provide more provider-specific flexibility, but migration may require changes to networking, identity, monitoring, security, backup, licensing and high availability.
6. File or object-storage offload
Move archives, backup repositories or selected file data to cloud storage while keeping compute on-premises. A gateway such as AWS Storage Gateway can expose selected cloud-backed storage functions to on-premises environments, including VMware, Hyper-V and Linux KVM hosts. This is generally a better fit for controlled data movement or backup than for latency-sensitive production VM disks across a WAN.
Cloud storage economics
Cloud storage is elastic, not unlimited or free. Model:
Best Value
- MADE FOR THE MAKERS: Create; Explore; Store; The T7 Portable SSD delivers fast speeds and durable features to back up any endeavor; Build your video editing empire, file your photographs or back up your blogs all in an instant
- SHARE IDEAS IN A FLASH: Don’t waste a second waiting and spend more time doing; The T7 is embedded with PCIe NVMe technology that brings fast read and write speeds up to 1,050/1,000 MB/s¹, making it almost twice as fast as the T5
- ALWAYS MAKE THE SAVE: Compact design with massive capacity; With capacities up to 4TB, save exactly what you need to your drive – from large working files to game data and everything in between
- ADAPTS TO EVERY NEED: Whether using a PC or mobile phone, count on the T7 for extensive compatibility²; It’s a true team player when it comes to heavy-duty application usage or file-saving
- HI RESOLUTION VIDEO RECORDING: Record Ultra High Resolution (4K 60fs) videos directly onto the T7 Portable SSD with your favorite camera or mobile devices; Supports iPhone 15 Pro Res 4K at 60fps video and more³
- Provisioned capacity, including capacity reserved but not yet used
- Provisioned IOPS and throughput
- Snapshots and backup-retention duration
- Replication across zones or regions
- Inter-zone, inter-region and internet egress
- Standby disaster-recovery hosts and storage
- Managed VMware service and dedicated infrastructure charges
- Minimum capacity, host commitments and provider quotas
A smaller provisioned volume is not necessarily cheaper if it requires high IOPS, extensive snapshots or frequent cross-region transfers. Compare the cost of the complete recovery and operating architecture, not only the disk price. Use the official Azure Managed Disks, Amazon EBS and Google Cloud disk pricing pages for current regional calculations.
Common failure modes
Datastore exhaustion
Thin-provisioned disks, snapshots, clones, backup staging, replication journals, swap files, migration copies and rebuild overhead can fill a datastore even when individual guests report free space. Because the resource is shared, several VMs may be affected at once.
Snapshot sprawl
Snapshots are not backups. Write-heavy databases and log volumes can grow quickly, and deleting a snapshot may temporarily create additional I/O and space demand. Keep snapshots short-lived, documented and monitored.
Expansion stops at the virtual disk
The hypervisor or cloud console may report the new size while the guest still sees the old partition or filesystem. Always verify every layer.
Disk identification errors
On systems with several similarly sized disks, expanding the wrong device can cause an outage or data loss. Record device identifiers and confirm them from both the control plane and guest operating system.
Reclamation does not occur
Deleting files inside a guest may not immediately return blocks to a datastore or cloud volume. Reclamation can depend on discard/TRIM, zeroing, filesystem behavior, array support and migration operations. In applicable VMware environments, Broadcom discusses reclamation procedures including vmkfstools -K; follow the release-specific guidance rather than running it indiscriminately.
Performance mismatch
A capacity-rich but low-IOPS disk can degrade a database. Conversely, premium performance on an archive workload wastes money. Measure the workload before changing tiers.
Cloud latency and dependency failure
An application that performs well on a local SAN may fail when its disks or dependencies are separated by a WAN. Test latency, packet loss, DNS, identity, authentication, database dependencies and failover—not only sequential throughput.
Quick Recap
Choosing an approach
| Requirement | Likely direction |
|---|---|
| Predictable local latency and limited connectivity | Local, SAN or HCI storage with carefully selected tiers |
| Unknown growth with strong operations | Thin provisioning with quotas, trend alerts and a tested emergency plan |
| Stable, tightly controlled capacity | Thick provisioning or reserved capacity |
| Off-site retention and ransomware recovery | Immutable cloud backup or object-storage-based retention |
| Fast VMware migration with minimal guest change | Azure VMware Solution or VMware Cloud on AWS, after a full cost review |
| Long-term redesign and elastic services | Native cloud block, file, object or managed application services |
| Archive or backup access from on-premises | Cloud file/object storage or a suitable gateway, subject to latency testing |
Operational checklist
- Measure guest usage, virtual capacity and physical consumption separately.
- Record IOPS, throughput, latency, queue depth and burst behavior.
- Separate OS, data, log, temporary, backup and archive requirements where useful.
- Choose thick or thin provisioning deliberately.
- Monitor physical free space, overcommitment, snapshots and projected growth.
- Reserve capacity for rebuilds, migration, backup, failover and emergency growth.
- Confirm backups and recovery before resizing.
- Expand the control-plane disk, guest partition or LVM layer and filesystem in sequence.
- Check GPT/MBR, filesystem, provider, VM-generation and disk-type limits.
- Test online-resize eligibility instead of assuming zero downtime.
- Model IOPS, throughput, snapshots, replication and egress in cloud costs.
- Test application latency and complete failover workflows.
- Document the change and update capacity forecasts.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
