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 errorsiTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Thin disks grow as data is written; traditional thick disks reserve their configured capacity up front. That difference explains why a datastore can appear to lose far more space when a VM is created with thick disks, even if the guest operating system has barely used them. To find what is actually consuming storage, distinguish provisioned capacity from datastore consumption, then account for snapshots, other VM files, storage policies, and any thin provisioning in the storage array.
What “eating the datastore” can mean
Capacity reports can describe different layers, and their numbers are not interchangeable:
- Configured or provisioned capacity: the maximum virtual-disk size assigned to a VM. A thin disk can have a large configured size while occupying less physical space.
- Datastore consumption: space currently attributed to files on the datastore. On traditional VMFS, a thick disk can consume its full configured capacity from creation, while a thin disk grows as blocks are written.
- Storage-array consumption: the physical capacity used by the array’s pool. If both the hypervisor and array provision thinly, the array’s usage may differ from what vSphere reports.
- Policy-reserved capacity: on vSAN, storage policy reservations and consumption affect reported capacity; they should not be read as though they were traditional VMFS thick allocation.
For a VMFS/VMDK overview, Broadcom explains the provisioning and zeroing behavior in its virtual-disk provisioning documentation. vSAN capacity and policy behavior is discussed separately in VMware’s vSAN space-efficiency overview and vSAN thin-provisioning article.
How thin and thick virtual disks allocate space
In Broadcom’s vSphere/VMFS terminology, there are three common VMDK types. “Thick” is not a single behavior: lazy-zeroed and eager-zeroed thick disks differ in when blocks are zeroed.
#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
| VMDK type | Space allocated at creation | When blocks are zeroed | Practical trade-off |
|---|---|---|---|
| Thin | Does not allocate the full disk capacity at creation | As blocks are first consumed | Uses less datastore space initially, but can grow and contribute to overcommit risk |
| Thick lazy-zeroed | Full disk capacity is allocated | When a block is first accessed | Reserves capacity up front, but first use still involves zeroing |
| Eager-zeroed thick | Full disk capacity is allocated | At creation | Completes allocation and zeroing up front, at the cost of initial capacity and creation work |
These descriptions apply to the VMFS/VMDK behavior documented by Broadcom. Check the exact vSphere release, datastore type, storage policy, and array configuration before interpreting a particular capacity figure.
Why thin provisioning can run out of space
Thin provisioning makes it possible for the total configured capacity of virtual disks to exceed the datastore’s physical capacity. That is useful when disks are configured larger than the data guests currently store, but it shifts responsibility to capacity monitoring: if the disks grow faster than available backing space, the datastore can fill.
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.
Look at both the virtualization layer and the underlying storage pool, especially when the array also provisions thinly. Track available capacity and growth over time, and include snapshots and other VM files in the accounting. Microsoft’s documentation describes thin-provisioning capacity monitoring and allocation-status mechanisms in its thin provisioning overview. VMware’s performance material also cautions that thin-on-thin configurations need careful management: vSphere virtual-machine performance white paper.
There is no single free-space alarm percentage that fits every deployment. Set alerts with the datastore’s growth rate, the array’s behavior, and the consequences of running out of capacity in mind; use the applicable platform and storage-vendor guidance.
Rank #3
- 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
Does one disk type perform better?
There is no universal performance winner. The key difference is preparation of newly consumed blocks: thin disks allocate and zero blocks as needed; lazy-zeroed thick disks allocate at creation but defer zeroing until first use; eager-zeroed thick disks do both at creation.
That work may affect writes when a workload consumes many new blocks, particularly large sequential writes. Broadcom says ordinary production performance is similar across provisioning types, while large-scale sequential writes can reveal differences. The impact depends on workload, overall system load, the storage array, and how the array handles zero data. Its explanation is in Understanding large-scale sequential write performance in VMDKs residing on VMFS datastores.
Rank #4
- 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
So eager-zeroed thick may avoid first-use preparation during those writes, but converting every disk to that type is not a general application-performance fix. Evaluate the workload and array rather than assuming the provisioning label alone predicts performance.
The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →How to find what is consuming space
- Compare configured capacity with datastore-used capacity. Review each virtual disk’s provisioned size and actual datastore consumption as separate values; a thin disk’s configured maximum is not its current physical use.
- Identify the disk type and storage context. Determine whether each VMDK is thin, thick lazy-zeroed, or eager-zeroed thick. Check whether a vSAN policy reservation or array-side thin provisioning changes what the reported figures mean.
- Account for files beyond the virtual disks. Check snapshots, swap, and other VM files; disk allocation alone may not explain all datastore usage.
- Check capacity at both storage layers. Review datastore free space and growth as well as the underlying array pool, with particular care for thin-on-thin configurations.
- Plan conversions before changing a disk. Broadcom advises confirming a valid backup and sufficient target capacity before conversion. Its virtual-disk conversion guidance notes that conversion time depends on array performance.
Which type should you choose?
- Choose thin when conserving initial datastore capacity matters and you can monitor growth reliably across the hypervisor and storage array.
- Choose thick lazy-zeroed when you want disk capacity allocated up front but do not need zeroing completed at creation.
- Choose eager-zeroed thick when the workload or platform requirement justifies completing allocation and zeroing in advance, and the up-front capacity and creation work are acceptable.
For any of these choices, use the storage platform’s current guidance and the behavior of the specific datastore and array—not the disk label alone—to interpret reservation, consumption, and performance.
Quick Recap
Best Value
- NEARLY 2X FASTER THAN OUR PREVIOUS GENERATION(8) – move 1,000 high-res photos in under 60 seconds(6) with up to 2000MB/s transfer speeds(2).
- IP65 RATING AND UP TO 3M DROP PROTECTION(3) – protects against spills and drops.
- POCKET-SIZED – fits easily in pockets and small bags.
- SPACE TO OWN YOUR AI CONTENT – speed and capacity to download your high-res clips and photo edits.
- 256-BIT AES ENCRYPTION(4) – helps keep private files secure with password protection.
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.
