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From: "Fabian Grünbichler" <f.gruenbichler@proxmox.com>
To: "DERUMIER, Alexandre" <alexandre.derumier@groupe-cyllene.com>,
	"pve-devel@lists.proxmox.com" <pve-devel@lists.proxmox.com>
Subject: Re: [pve-devel] [PATCH v3 qemu-server 08/11] blockdev: convert drive_mirror to blockdev_mirror
Date: Mon, 13 Jan 2025 10:55:36 +0100 (CET)	[thread overview]
Message-ID: <739009584.2555.1736762136125@webmail.proxmox.com> (raw)
In-Reply-To: <851960591.2541.1736761924866@webmail.proxmox.com>


> Fabian Grünbichler <f.gruenbichler@proxmox.com> hat am 13.01.2025 10:52 CET geschrieben:
> 
>  
> > DERUMIER, Alexandre <alexandre.derumier@groupe-cyllene.com> hat am 13.01.2025 09:27 CET geschrieben:
> > 
> >  
> > > +    my $path = PVE::Storage::path($storecfg, $volid);
> > 
> > >>is this guaranteed to be stable? also across versions? and including
> > >>external storage plugins?
> > 
> > it can't be different than the value we have use for command line
> > generation. But I think that I should use $path directly (It's working
> > for block/file  ,  but I think it'll not work with ceph,gluster,...)
> > I need to reuse the code used to generated the blockdev commande line.
> > 
> > Another way, maybe a better way,is to parse the tree from the top node
> > (the throttle-group) where the name is fixed.  and look for fmt|file
> > chain attached to this node.
> > 
> > (I just need need to check when we are a doing live renaming, we have 2
> > files nodes, with the newer file node not attached to the tree before
> > the switch)
> > 
> > 
> > 
> > > +
> > > +    my $node = find_blockdev_node($nodes, $path, 'fmt');
> > 
> > >>that one is only added in a later patch.. but I don't think lookups
> > >>by path are a good idea, we should probably have a deterministic node
> > >>naming concept instead? e.g., encode the drive + snapshot name?
> > 
> > I really would like to have something deterministic but:
> > 
> > - devices node are 31 characters max.   (snapshot name can be more big)
> > - we can't rename a node  (but we are renaming files for snapshot over
> > time)
> > 
> > 
> > As Fiona said, we could have random names and do 1 lookup each time to
> > list them.
> > 
> > (I really need to have our own name, because blockdev-reopen, for live
> > renaming of files, is not working with autogenerated block# name)
> 
> something like this was what I was afraid of ;) this basically means we need to have some way to lookup the nodes based on the structure of the graph, which probably also means verifying that the structure matches the expected one (e.g., if we have X snapshots, we expect N nodes, if we currently have operation A going on, there should be an extra node, etc.pp. - and then we can "know" that the seventh node from the bottom must be snapshot 'foobar' ;)). relying on $path being stable definitely won't work.

something more to add to this - if it is impossible to map back using the structure alone, we might need to somehow keep track ourselves for the full livecycle of the VM? e.g., find a way to attach the "volid+snap" information to a block node as metadata, or to add such a mapping inside the VM or alongside it? OTOH, that approach would then break if a user does a manual QMP block operation (but those are error prone already anyway)


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  reply	other threads:[~2025-01-13  9:55 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20241216091229.3142660-1-alexandre.derumier@groupe-cyllene.com>
2024-12-16  9:12 ` [pve-devel] [PATCH v1 pve-qemu 1/1] add block-commit-replaces option patch Alexandre Derumier via pve-devel
2025-01-08 13:27   ` Fabian Grünbichler
2025-01-10  7:55     ` DERUMIER, Alexandre via pve-devel
     [not found]     ` <34a164520eba035d1db5f70761b0f4aa59fecfa5.camel@groupe-cyllene.com>
2025-01-10  9:15       ` Fiona Ebner
2025-01-10  9:32         ` DERUMIER, Alexandre via pve-devel
     [not found]         ` <1e45e756801843dd46eb6ce2958d30885ad73bc2.camel@groupe-cyllene.com>
2025-01-13 14:28           ` Fiona Ebner
2025-01-14 10:10             ` DERUMIER, Alexandre via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 01/11] blockdev: cmdline: convert drive to blockdev syntax Alexandre Derumier via pve-devel
2025-01-08 14:17   ` Fabian Grünbichler
2025-01-10 13:50     ` DERUMIER, Alexandre via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 pve-storage 1/3] qcow2: add external snapshot support Alexandre Derumier via pve-devel
2025-01-09 12:36   ` Fabian Grünbichler
2025-01-10  9:10     ` DERUMIER, Alexandre via pve-devel
     [not found]     ` <f25028d41a9588e82889b3ef869a14f33cbd216e.camel@groupe-cyllene.com>
2025-01-10 11:02       ` Fabian Grünbichler
2025-01-10 11:51         ` DERUMIER, Alexandre via pve-devel
     [not found]         ` <1caecaa23e5d57030a9e31f2f0e67648f1930d6a.camel@groupe-cyllene.com>
2025-01-10 12:20           ` Fabian Grünbichler
2025-01-10 13:14             ` DERUMIER, Alexandre via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 02/11] blockdev: fix cfg2cmd tests Alexandre Derumier via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 pve-storage 2/3] lvmplugin: add qcow2 snapshot Alexandre Derumier via pve-devel
2025-01-09 13:55   ` Fabian Grünbichler
2025-01-10 10:16     ` DERUMIER, Alexandre via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 03/11] blockdev : convert qemu_driveadd && qemu_drivedel Alexandre Derumier via pve-devel
2025-01-08 14:26   ` Fabian Grünbichler
2025-01-10 14:08     ` DERUMIER, Alexandre via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 pve-storage 3/3] storage: vdisk_free: remove external snapshots Alexandre Derumier via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 04/11] blockdev: vm_devices_list : fix block-query Alexandre Derumier via pve-devel
2025-01-08 14:31   ` Fabian Grünbichler
2025-01-13  7:56     ` DERUMIER, Alexandre via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 05/11] blockdev: convert cdrom media eject/insert Alexandre Derumier via pve-devel
2025-01-08 14:34   ` Fabian Grünbichler
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 06/11] blockdev: block_resize: convert to blockdev Alexandre Derumier via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 07/11] blockdev: nbd_export: block-export-add : use drive-$id for nodename Alexandre Derumier via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 08/11] blockdev: convert drive_mirror to blockdev_mirror Alexandre Derumier via pve-devel
2025-01-08 15:19   ` Fabian Grünbichler
2025-01-13  8:27     ` DERUMIER, Alexandre via pve-devel
     [not found]     ` <0d0d4c4d73110cf0e692cae0ee65bf7f9a6ce93a.camel@groupe-cyllene.com>
2025-01-13  9:52       ` Fabian Grünbichler
2025-01-13  9:55         ` Fabian Grünbichler [this message]
2025-01-13 10:47         ` DERUMIER, Alexandre via pve-devel
2025-01-13 13:42           ` Fiona Ebner
2025-01-14 10:03             ` DERUMIER, Alexandre via pve-devel
     [not found]             ` <fa38efbd95b57ba57a5628d6acfcda9d5875fa82.camel@groupe-cyllene.com>
2025-01-15  9:39               ` Fiona Ebner
2025-01-15  9:51                 ` Fabian Grünbichler
2025-01-15 10:06                   ` Fiona Ebner
2025-01-15 10:15                     ` Fabian Grünbichler
2025-01-15 10:46                       ` Fiona Ebner
2025-01-15 10:50                         ` Fabian Grünbichler
2025-01-15 11:01                           ` Fiona Ebner
2025-01-15 13:01                       ` DERUMIER, Alexandre via pve-devel
2025-01-16 14:56                     ` DERUMIER, Alexandre via pve-devel
2025-01-15 10:15                   ` DERUMIER, Alexandre via pve-devel
     [not found]         ` <c1559499319052d6cf10900efd5376c12389a60f.camel@groupe-cyllene.com>
2025-01-13 13:31           ` Fabian Grünbichler
2025-01-20 13:37             ` DERUMIER, Alexandre via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 09/11] blockdev: mirror: change aio on target if io_uring is not default Alexandre Derumier via pve-devel
2025-01-09  9:51   ` Fabian Grünbichler
2025-01-13  8:38     ` DERUMIER, Alexandre via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 10/11] blockdev: add backing_chain support Alexandre Derumier via pve-devel
2025-01-09 11:57   ` Fabian Grünbichler
2025-01-13  8:53     ` DERUMIER, Alexandre via pve-devel
2024-12-16  9:12 ` [pve-devel] [PATCH v3 qemu-server 11/11] qcow2: add external snapshot support Alexandre Derumier via pve-devel
2025-01-09 11:57   ` Fabian Grünbichler
2025-01-09 13:19     ` Fabio Fantoni via pve-devel
2025-01-20 13:44       ` DERUMIER, Alexandre via pve-devel
     [not found]       ` <3307ec388a763510ec78f97ed9f0de00c87d54b5.camel@groupe-cyllene.com>
2025-01-20 14:29         ` Fabio Fantoni via pve-devel
     [not found]         ` <6bdfe757-ae04-42e1-b197-c9ddb873e353@m2r.biz>
2025-01-20 14:41           ` DERUMIER, Alexandre via pve-devel
2025-01-13 10:08     ` DERUMIER, Alexandre via pve-devel
     [not found]     ` <0ae72889042e006d9202e837aac7ecf2b413e1b4.camel@groupe-cyllene.com>
2025-01-13 13:27       ` Fabian Grünbichler
2025-01-13 18:07         ` DERUMIER, Alexandre via pve-devel
2025-01-13 18:58           ` DERUMIER, Alexandre via pve-devel

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