vSphere 5 brought new filesystem VMFS 5 – your questions about it?
Yesterday I took the VCP 510 exam. I passed fine, and I updated the post – Resources to prepare your VCP exam – VCP 510 – with my own experience there. And sure, there has been questions about the new VMFS 5 – new version of VMware Filesystem. I can't tell your what exactly those questions were about, but instead I will point you to VMware KB article which discuss some interesting questions from users like you and me concerning the new file system.
One of the sections which is very important in the new vSphere 5 is storage changes with the new, updated VMFS-5. You might have already read my post – VMFS-5 introduced in vSphere 5, where you could see that:
VMFS-5 uses GPT (GUID Partition Table) rather than MBR, which allows for pass-through RDM files greater than 2TB. When you upgrade from VMFS-3 to VMFS-5 the MBR partition table is still used, but when the VMFS-5 volume is grown above 2TB, it automatically & seamlessly switches from MBR to GPT (GUID Partition Table) with no impact to the running VMs.
Another aspect of the upgrade process. You might see a message saying that:
There are hosts accessing this datastore which don't support VMFS-5
You basically won't be able to upgrade your datastores to VMFS-5 if you still have hosts with ESXi 4.x installed, since those still uses VMFS version 3.x. The only way is to first upgrade your hosts to ESXi 5 and then upgrade your datastores. (actually Once the datastore has been upgraded to VMFS-5, it is no longer visible on legacy ESXi hosts. ).
A quick quote from the KB Article:
What are the limitations for VMFS-5?
– VMFS-5 still limits the number of extents to 32 and the total datastore size to 64TB, but the individual extents are no longer limited
to 2TB each. For example, a datastore can be created with a LUN size of 64TB, or a datastore can be created with up to 32 extents up
to maximum size of 64TB.
– Only pass-through RDMs can be created with a size >2TB. Non-pass-through RDMs and virtual disk files are still limited to 512B ~ 2TB.
– Passthrough RDMs are supported up to ~60TB in size.
– Both upgraded and newly-created VMFS-5 volumes supported the larger Passthrough RDM size.
There are other sections in the document, like Why would I need to upgrade to VMFS-5?
– Performance increase and scalability……
– VMFS-5 does not use SCSI-2 Reservations, but uses the ATS VAAI primitives (on arrays which does support this feature)
I can highly recommend to read this KB.
Source: You can find the whole KB article here – vSphere 5 FAQ: VMFS-5