Clone on boot #27
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Clone on boot #27
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added 10 commits
July 14, 2015 15:32
This allows datapath plugins to be clever, creating temporary linked clones on local storage or enabling caching. Signed-off-by: David Scott <dave.scott@eu.citrix.com>
This creates the foundation for watching the datapath plugins. Signed-off-by: David Scott <dave.scott@eu.citrix.com>
We keep a table of the known datapath plugins so we can choose the most appropriate one to use. Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Upon VDI.epoch_begin with persistent = false, we call `Volume.stat` to discover the possible URIs. We look first for a datapath plugin which can perform clone-on-boot natively (e.g. by truncating vhd leaves) and delegate to that. If a datapath plugin doesn't exist then we will fall back to the Volume.clone / Volume.destroy API. This will be done in a later patch. We expose the VDI_RESET_ON_BOOT/2 capability if the volume plugin supports VDI_CLONE. This isn't ideal as it won't cover the case where a LUN-per-VDI SR which doesn't support VDI.CLONE nevertheless can support clone-on-boot if the tapdisk datapath is used. Signed-off-by: David Scott <dave.scott@eu.citrix.com>
When the toolstack calls VDI.epoch_begin we query the volume and choose the datapath. If the datapath doesn't expose the NONPERSISTENT capability then we use Volume.clone to make a temporary volume. The key of the volume is added to the metadata of the original volume. In subsequent functions we call `Volume.stat` on the original volume, discover the _clone_on_boot_key and follow the link to the temporary volume. The temporary volume is destroyed on VDI.epoch_end and on Volume.destroy of the original volume. Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Signed-off-by: David Scott <dave.scott@eu.citrix.com>
We do all clone-on-boot actions during the VDI.epoch_begin and VDI.epoch_end, so we can ignore this one. Signed-off-by: David Scott <dave.scott@eu.citrix.com>
This avoids tripping up if Uri.(to_string (of_string x)) <> x from the point-of-view of the backend. Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Signed-off-by: David Scott <dave.scott@eu.citrix.com>
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travis is failing with because I haven't released the xcp-idl changes yet. |
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If
Volume.statreturns multiple URIs, we will prefer to use a datapath plugin that exposes theNONPERSISTENTfeature. Otherwise we will fall back to usingVolume.clone.Note that we use the new
Volume.setandVolume.unsetto store the key of the temporary clone-on-boot volume. We dereference this pointer beforeDatapath.attachetc. We omit these temporary volumes fromSR.lsand we guarantee to clean them up onVDI.epoch_end,VDI.destroy, orVDI.attach(in the case where one leaked over a crashed and the VM restarted).