SPDK requires taking over the device. OP is correct if you want to have a multi tenant application where the disk is also used for other things.

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dataflow 6 days ago | parent [-]

Not an expert on this but I think that's... half-true? There is namespace support which should allow multiple users I think (?), but it does still require direct device access.

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vlovich123 6 days ago | parent [-]

Namespaces are a hack device manufacturers came up with to try to make this work anyway. Namespaces at the device level are a terrible idea IMP because it’s still not multi tenant - your just carving up a single drive into logically separated chunks that you have to decide on up front. So you have to say “application X gets Y% of the drive while application A gets B%”. It’s an expensive static allocation that’s not self adjusting based on actual dynamic usage.

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10000truths 6 days ago | parent | next [-]

Dynamic allocation implies the ability to shrink as well as grow. How do you envision shrinking an allocation of blocks to which your tenant has already written data that is (naturally) expected to be durable in perpetuity?

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vlovich123 5 days ago | parent [-]

you mean something filesystems do as a matter of course? Ignoring resizing them which is also supported through supporting technologies I’m not talking about partitioning a drive. You can have different applications sharing a filesystem just fine, with each application growing how much space it uses naturally as usage increases or shrinks. Partitioning and namespaces are similar (namespaces are significantly more static) in that you have to make decisions about the future really early vs a normal file on a filesystem growing over time.

	▲	10000truths 5 days ago \| parent [-]
		If you're assuming that every tenant's block device is storing a filesystem, then you're not providing your tenant a block device, you're providing your tenant a filesystem. And if you're providing them a filesystem, then you should use something like LVM for dynamic partitioning. The point of NVMe namespaces is to partition at the block device layer. To turn one physical block device into multiple logical block devices, each with their own queues, LBA space, etc. It's for when your tenants are interacting with the block device directly. That's not a hack, that's intended functionality.

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6 days ago | parent | prev [-]

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