Hi,
We are seeing an issue where flash storage looks to be correctly configured and detected in VSAN, but not used:
Looking a bit deeper, it appears that the NVMe disks aren't eligible due to an existing partition on the disk:
[root@localhost:~] esxcli storage vflash device list
Name Size Is Local Is Used in vflash Eligibility
-------------------------------------------------------------------------------- ------ -------- ----------------- ----------------------
t10.NVMe____INTEL_SSDPEDMD800G4_____________________CVFT607600A9800CGN__00000001 763097 true false Other partitions exist
The partitions on the disk look like so:
[root@localhost:~] partedUtil getptbl /dev/disks/t10.NVMe____INTEL_SSDPEDMD800G4_____________________CVFT607600A9800CGN__00000001
gpt
97281 255 63 1562824368
1 2048 6143 381CFCCC728811E092EE000C2911D0B2 vsan 0
2 6144 1562824334 77719A0CA4A011E3A47E000C29745A24 virsto 0
Interested to hear comments from other members on what might be causing this? The SSD was never used for any other function.
Thanks
Hello George,
Those two partitions are vSAN partitions created when the disk-group was created.
Are you wondering why the used space on the NVMe is 0B?
This is because the cache-tier device is not used for storage, it is used to stage and de-stage data from the capacity-tier devices in this disk-group so nothing is permanently stored on this device.
These commands should show you that this is in use by vSAN and the configured purpose:
#vdq -q
#esxcli vsan storage list
(e.g. the cache-tier NVMe will show as "Is Capacity Tier: false" )
Bob
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Hello George,
Those two partitions are vSAN partitions created when the disk-group was created.
Are you wondering why the used space on the NVMe is 0B?
This is because the cache-tier device is not used for storage, it is used to stage and de-stage data from the capacity-tier devices in this disk-group so nothing is permanently stored on this device.
These commands should show you that this is in use by vSAN and the configured purpose:
#vdq -q
#esxcli vsan storage list
(e.g. the cache-tier NVMe will show as "Is Capacity Tier: false" )
Bob
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Hi Bob
Thanks for your reply, makes sense. So can I take it from that response that there is no way to see how *much* of the SSD is being used? Not that it matters I suppose as it can't be used for anything else, but out of interest it would be good to know.
I had a suspicion that everything was working correctly and glad to hear that is the case!
George
Hello George,
Glad I could help clarify things here.
This won't be a static amount, this is constantly fluctuating as data is staged and de-staged, there *are* means of looking at different usage levels using vsish but this is not trivial. Also there can be other factors on SSDs relating to how much space is really *free* such as Manufacturer-set Over-provisioning and Dynamic over-provisioning.
Bob
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