Ceph - Bus/Device

Ma907xb

Well-Known Member
Dec 26, 2018
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Hello,

Which Bus/Device is recommended for installing on top of a ceph pool? I'm just running a 3 node cluster with CEPH. I was recommended to use SCSI as well as checking the discard option, but I don't understand why. What should be selected for device #?

Could someone offer an explanation?

recommended setting.JPG

Thank you!
 
SCSI has the best performance as acts the most like a real drive to the OS.

Discard will make sure the OS passes down to CEPH when a file is deleted so the space can be freeded up in CEPH otherwise old data wont be removed from the CEPh Storage layer.

Device# leave as 0, if you had a second disk this would automatically change to 1 for example.
 
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SCSI has the best performance as acts the most like a real drive to the OS.

Discard will make sure the OS passes down to CEPH when a file is deleted so the space can be freeded up in CEPH otherwise old data wont be removed from the CEPh Storage layer.

Thank you.

Device# leave as 0, if you had a second disk this would automatically change to 1 for example.

The device number seems to be corresponding with the # of OSDs. Is this option just not applicable to a cluster with CEPH?
 
The device number seems to be corresponding with the # of OSDs. Is this option just not applicable to a cluster with CEPH?
The device number is the count of disks for this VM. This is solely a numbering for the VM and has nothing to do with Ceph.
 
SCSI has the best performance as acts the most like a real drive to the OS.

Discard will make sure the OS passes down to CEPH when a file is deleted so the space can be freeded up in CEPH otherwise old data wont be removed from the CEPh Storage layer.

Device# leave as 0, if you had a second disk this would automatically change to 1 for example.

is there anyway (CLI?) to check that this box was ticked after the VM was created?