Hi, I posted draft PRs for engine[1] and vdsm[2], they are still raw and I only tested running starting VMs with ceph. If you can apply the changes for lightos (only vdsm should be needed) and try it out it would be great :) Also, if you have any suggestions/comments/etc feel free to comment on the PRs directly
If you don't want to build ovirt-engine from source, CI generated RPMs should be available in[3] (the job is still running while I'm writing this email) [1] https://github.com/oVirt/ovirt-engine/pull/104 [2] https://github.com/oVirt/vdsm/pull/89 [3] https://github.com/oVirt/ovirt-engine/actions/runs/1929008680 On Wed, Mar 2, 2022 at 4:55 PM Muli Ben-Yehuda <m...@lightbitslabs.com> wrote: > > Thanks for the update, Benny. How can I help? For example, would logs from > running the connector with the exact data it returns be useful? > > Cheers, > Muli > > On Tue, Mar 1, 2022 at 8:39 PM Benny Zlotnik <bzlot...@redhat.com> wrote: >> >> Hi, >> >> Just by browsing the code, I can think of one issue in[1], as a result >> of[2] where we only considered iscsi and rbd drivers, I suspect your >> driver will go into this branch, based on the issue in the 4.3 logs I >> went over: >> backend/manager/modules/vdsbroker/src/main/java/org/ovirt/engine/core/vdsbroker/builder/vminfo/LibvirtVmXmlBuilder.java >> >> } else if (managedBlockStorageDisk.getCinderVolumeDriver() >> == CinderVolumeDriver.BLOCK) { >> Map<String, Object> attachment = >> (Map<String, Object>) >> managedBlockStorageDisk.getDevice().get(DeviceInfoReturn.ATTACHMENT); >> metadata = Map.of( >> "GUID", >> (String)attachment.get(DeviceInfoReturn.SCSI_WWN), >> "managed", "true" >> >> Which will make it go into the wrong branch in clientIF.py, appending >> the empty GUID to /dev/mapper. Perhaps it is possible workaround it in >> clientIF if you just want to try and get the VM started for now, by >> checking if GUID is empty and deferring to: >> volPath = drive['path'] >> >> But as discussed in this thread, our attempt at constructing the >> stable paths ourselves doesn't really scale. After further discussion >> with Nir I started working on creating a link in vdsm in >> managevolume.py#attach_volume to the path returned by the driver, and >> engine will use our link to run the VMs. >> This should simplify the code and resolve the live VM migration issue. >> I had some preliminary success with this so I'll try to post the >> patches soon >> >> >> [1] >> https://github.com/oVirt/vdsm/blob/d957a06a4d988489c83da171fcd9cfd254b12ca4/lib/vdsm/clientIF.py#L462 >> [2] >> https://github.com/oVirt/ovirt-engine/blob/24530d17874e20581deee4b0e319146cdcacb8f5/backend/manager/modules/vdsbroker/src/main/java/org/ovirt/engine/core/vdsbroker/builder/vminfo/LibvirtVmXmlBuilder.java#L2424 >> >> >> >> >> >> >> >> >> >> >> On Tue, Mar 1, 2022 at 6:12 PM Muli Ben-Yehuda <m...@lightbitslabs.com> >> wrote: >> > >> > Will this support require changes in ovirt-engine or just in vdsm? I have >> > started to look into vdsm's managedvolume.py and its tests and it seems >> > like adding support for LightOS there should be pretty simple (famous last >> > words...). Should this be enough or do you think it will require changes >> > in other parts of ovirt as well? >> > >> > Cheers, >> > Muli >> > >> > On Mon, Feb 28, 2022 at 9:09 AM Nir Soffer <nsof...@redhat.com> wrote: >> >> >> >> On Fri, Feb 25, 2022 at 12:04 PM Gorka Eguileor <gegui...@redhat.com> >> >> wrote: >> >> > >> >> > On 24/02, Nir Soffer wrote: >> >> > > On Thu, Feb 24, 2022 at 8:46 PM Gorka Eguileor <gegui...@redhat.com> >> >> > > wrote: >> >> > > > >> >> > > > On 24/02, Nir Soffer wrote: >> >> > > > > On Thu, Feb 24, 2022 at 6:35 PM Muli Ben-Yehuda >> >> > > > > <m...@lightbitslabs.com> wrote: >> >> > > > > > >> >> > > > > > On Thu, Feb 24, 2022 at 6:28 PM Nir Soffer <nsof...@redhat.com> >> >> > > > > > wrote: >> >> > > > > >> >> >> > > > > >> On Thu, Feb 24, 2022 at 6:10 PM Muli Ben-Yehuda >> >> > > > > >> <m...@lightbitslabs.com> wrote: >> >> > > > > >> > >> >> > > > > >> > On Thu, Feb 24, 2022 at 3:58 PM Nir Soffer >> >> > > > > >> > <nsof...@redhat.com> wrote: >> >> > > > > >> >> >> >> > > > > >> >> On Wed, Feb 23, 2022 at 6:24 PM Muli Ben-Yehuda >> >> > > > > >> >> <m...@lightbitslabs.com> wrote: >> >> > > > > >> >> > >> >> > > > > >> >> > Thanks for the detailed instructions, Nir. I'm going to >> >> > > > > >> >> > scrounge up some hardware. >> >> > > > > >> >> > By the way, if anyone else would like to work on NVMe/TCP >> >> > > > > >> >> > support, for NVMe/TCP target you can either use Lightbits >> >> > > > > >> >> > (talk to me offline for details) or use the upstream >> >> > > > > >> >> > Linux NVMe/TCP target. Lightbits is a clustered storage >> >> > > > > >> >> > system while upstream is a single target, but the client >> >> > > > > >> >> > side should be close enough for vdsm/ovirt purposes. >> >> > > > > >> >> >> >> > > > > >> >> I played with NVMe/TCP a little bit, using qemu to create a >> >> > > > > >> >> virtual >> >> > > > > >> >> NVMe disk, and export >> >> > > > > >> >> it using the kernel on one VM, and consume it on another VM. >> >> > > > > >> >> https://futurewei-cloud.github.io/ARM-Datacenter/qemu/nvme-of-tcp-vms/ >> >> > > > > >> >> >> >> > > > > >> >> One question about device naming - do we always get the >> >> > > > > >> >> same name of the >> >> > > > > >> >> device in all hosts? >> >> > > > > >> > >> >> > > > > >> > >> >> > > > > >> > No, we do not, see below how we handle migration in os_brick. >> >> > > > > >> > >> >> > > > > >> >> To support VM migration, every device must have unique name >> >> > > > > >> >> in the cluster. >> >> > > > > >> >> With multipath we always have unique name, since we disable >> >> > > > > >> >> "friendly names", >> >> > > > > >> >> so we always have: >> >> > > > > >> >> >> >> > > > > >> >> /dev/mapper/{wwid} >> >> > > > > >> >> >> >> > > > > >> >> With rbd we also do not use /dev/rbdN but a unique path: >> >> > > > > >> >> >> >> > > > > >> >> /dev/rbd/poolname/volume-vol-id >> >> > > > > >> >> >> >> > > > > >> >> How do we ensure cluster-unique device path? If os_brick >> >> > > > > >> >> does not handle it, we >> >> > > > > >> >> can to do in ovirt, for example: >> >> > > > > >> >> >> >> > > > > >> >> /run/vdsm/mangedvolumes/{uuid} -> /dev/nvme7n42 >> >> > > > > >> >> >> >> > > > > >> >> but I think this should be handled in cinderlib, since >> >> > > > > >> >> openstack have >> >> > > > > >> >> the same problem with migration. >> >> > > > > >> > >> >> > > > > >> > >> >> > > > > >> > Indeed. Both the Lightbits LightOS connector and the nvmeof >> >> > > > > >> > connector do this through the target provided namespace >> >> > > > > >> > (LUN) UUID. After connecting to the target, the connectors >> >> > > > > >> > wait for the local friendly-named device file that has the >> >> > > > > >> > right UUID to show up, and then return the friendly name. So >> >> > > > > >> > different hosts will have different friendly names, but the >> >> > > > > >> > VMs will be attached to the right namespace since we return >> >> > > > > >> > the friendly name on the current host that has the right >> >> > > > > >> > UUID. Does this also work for you? >> >> > > > > >> >> >> > > > > >> It will not work for oVirt. >> >> > > > > >> >> >> > > > > >> Migration in oVirt works like this: >> >> > > > > >> >> >> > > > > >> 1. Attach disks to destination host >> >> > > > > >> 2. Send VM XML from source host to destination host, and start >> >> > > > > >> the >> >> > > > > >> VM is paused mode >> >> > > > > >> 3. Start the migration on the source host >> >> > > > > >> 4. When migration is done, start the CPU on the destination >> >> > > > > >> host >> >> > > > > >> 5. Detach the disks from the source >> >> > > > > >> >> >> > > > > >> This will break in step 2, since the source xml refer to nvme >> >> > > > > >> device >> >> > > > > >> that does not exist or already used by another VM. >> >> > > > > > >> >> > > > > > >> >> > > > > > Indeed. >> >> > > > > > >> >> > > > > >> To make this work, the VM XML must use the same path, existing >> >> > > > > >> on >> >> > > > > >> both hosts. >> >> > > > > >> >> >> > > > > >> The issue can be solved by libvirt hook updating the paths >> >> > > > > >> before qemu >> >> > > > > >> is started on the destination, but I think the right way to >> >> > > > > >> handle this is to >> >> > > > > >> have the same path. >> >> > > > > > >> >> > > > > > >> >> > > > > > You mentioned above that it can be handled in ovirt (c.f., >> >> > > > > > /run/vdsm/mangedvolumes/{uuid} -> /dev/nvme7n42), which seems >> >> > > > > > like a reasonable approach given the constraint imposed by the >> >> > > > > > oVirt migration flow you outlined above. What information does >> >> > > > > > vdsm need to create and use the >> >> > > > > > /var/run/vdsm/managedvolumes/{uuid} link? Today the connector >> >> > > > > > does (trimmed for brevity): >> >> > > > > > >> >> > > > > > def connect_volume(self, connection_properties): >> >> > > > > > device_info = {'type': 'block'} >> >> > > > > > uuid = connection_properties['uuid'] >> >> > > > > > device_path = self._get_device_by_uuid(uuid) >> >> > > > > > device_info['path'] = device_path >> >> > > > > > return device_info >> >> > > > > >> >> > > > > I think we have 2 options: >> >> > > > > >> >> > > > > 1. unique path created by os_brick using the underlying uuid >> >> > > > > >> >> > > > > In this case the connector will return the uuid, and ovirt will >> >> > > > > use >> >> > > > > it to resolve the unique path that will be stored and used on >> >> > > > > engine >> >> > > > > side to create the vm xml. >> >> > > > > >> >> > > > > I'm not sure how the connector should return this uuid. Looking >> >> > > > > in current >> >> > > > > vdsm code: >> >> > > > > >> >> > > > > if vol_type in ("iscsi", "fibre_channel"): >> >> > > > > if "multipath_id" not in attachment: >> >> > > > > raise se.ManagedVolumeUnsupportedDevice(vol_id, >> >> > > > > attachment) >> >> > > > > # /dev/mapper/xxxyyy >> >> > > > > return os.path.join(DEV_MAPPER, >> >> > > > > attachment["multipath_id"]) >> >> > > > > elif vol_type == "rbd": >> >> > > > > # /dev/rbd/poolname/volume-vol-id >> >> > > > > return os.path.join(DEV_RBD, >> >> > > > > connection_info['data']['name']) >> >> > > > > >> >> > > > > os_brick does not have a uniform way to address different devices. >> >> > > > > >> >> > > > > Maybe Gorka can help with this. >> >> > > > >> >> > > > Hi, >> >> > > > >> >> > > > That is true, because in OpenStack we haven't had the need to have >> >> > > > the >> >> > > > same path on every host or even on the same host during different >> >> > > > connections. >> >> > > > >> >> > > > For nvme a new `elif` clause could be added there, though it will >> >> > > > be a >> >> > > > bit trickier, because the nvme connection properties format are a >> >> > > > bit of >> >> > > > a mess... >> >> > > > >> >> > > > We have 2 different formats for the nvme properties, and the wwid >> >> > > > that >> >> > > > appears in symlink /dev/disk/by-id/nvme-<wwid> may or may not be the >> >> > > > volume id, may be the uuid in the connection info if present or the >> >> > > > nguid if the nvme device doesn't have uuid. >> >> > > > >> >> > > > For these reasons I would recommend not relying on the connection >> >> > > > information and relying on the path from the attachment instead. >> >> > > > >> >> > > > Something like this should be probably fine: >> >> > > > >> >> > > > elif vol_type == 'nvme': >> >> > > > device_name = os.path.basename(attachment['path']) >> >> > > > controller = device_name.rsplit('n', 1)[0] >> >> > > > wwid_filename = >> >> > > > f'/sys/class/nvme/{controller}/{device_name}/wwid' >> >> > > > with open(wwid_filename, 'r') as f: >> >> > > > uuid = f.read().strip() >> >> > > > return os.path.join('/dev/disk/by-id/nvme-', uuid) >> >> > > >> >> > > Thanks Gorka! >> >> > > >> >> > > but isn't this duplicating logic already in os brick? >> >> > > https://github.com/openstack/os-brick/blob/56bf0272b55dcbbc7f5b03150973a80af1407f4f/os_brick/initiator/connectors/lightos.py#L193 >> >> > > >> >> > >> >> > Hi Nir, >> >> > >> >> > Oh! I thought we were talking about the generic NVMe-oF connector, >> >> > didn't know this was specific about the LightOS one. >> >> > >> >> > The link is used as an easy way to locate the volume, it doesn't mean >> >> > that it is returned to the caller of the `connect_volume` method. In >> >> > fact, we can see how that method actually returns the real path and not >> >> > the link's path: >> >> > >> >> > def _check_device_exists_using_dev_lnk(self, uuid): >> >> > lnk_path = f"/dev/disk/by-id/nvme-uuid.{uuid}" >> >> > --> if os.path.exists(lnk_path): >> >> > ^^^ Check link exists >> >> > >> >> > --> devname = os.path.realpath(lnk_path) >> >> > ^^^ Get the real path for the symlink >> >> > >> >> > --> if devname.startswith("/dev/nvme"): >> >> > ^^^ Make extra sure it's not pointing to something crazy >> >> > >> >> > LOG.info("LIGHTOS: devpath %s detected for uuid %s", >> >> > devname, uuid) >> >> > >> >> > --> return devname >> >> > ^^^ Return it >> >> > >> >> > return None >> >> > >> >> > > Another interesting detail is this wait: >> >> > > https://github.com/openstack/os-brick/blob/56bf0272b55dcbbc7f5b03150973a80af1407f4f/os_brick/initiator/connectors/lightos.py#L228 >> >> > > >> >> > > def _get_device_by_uuid(self, uuid): >> >> > > endtime = time.time() + self.WAIT_DEVICE_TIMEOUT >> >> > > while time.time() < endtime: >> >> > > try: >> >> > > device = self._check_device_exists_using_dev_lnk(uuid) >> >> > > if device: >> >> > > return device >> >> > > except Exception as e: >> >> > > LOG.debug(f'LIGHTOS: {e}') >> >> > > device = >> >> > > self._check_device_exists_reading_block_class(uuid) >> >> > > if device: >> >> > > return device >> >> > > >> >> > > time.sleep(1) >> >> > > return None >> >> > > >> >> > > The code does not explain why it tries to use the /dev/disk/by-id link >> >> > > and fallback to sysfs on errors. Based on our experience with udev, >> >> > > I guess that the author does not trust udev. I wonder if we can trust >> >> > > it as the stable device path. >> >> > > >> >> > >> >> > In my experience udev rules (which is different from udev itself) are >> >> > less that reliable as a way of finding devices when working "in the >> >> > wild". They are only reliable if you have full control over the host >> >> > system and are sure nobody (admin or distro) can break things. >> >> > >> >> > For reference, at Red Hat we have an RFE to improve os-brick [1] and >> >> > stop using symlinks at all. >> >> > >> >> > While they are not 100% reliable in the wild, they are quite reliable >> >> > once they are working on a specific system, which means that if we >> >> > confirm they are working on a system we can rely on them if no changes >> >> > are made on the system (and if CPU is not 100% during attachment). >> >> > >> >> > >> >> > [1]: https://bugzilla.redhat.com/show_bug.cgi?id=1697319 >> >> > >> >> > >> >> > > If we can trust this path, maybe os_brick can return the stable path >> >> > > in a uniform way for all kind of devices? >> >> > >> >> > I don't think this is likely to happen, because it has no real value for >> >> > OpenStack so it's unlikely to get prioritized (for coding and reviews). >> >> >> >> Since we cannot get a stable path from os-brick, and stable path is a >> >> oVirt >> >> specific requirement, we need to handle this in oVirt, similar to the way >> >> we >> >> handle multipath and rbd and traditional storage. >> >> >> >> Nir >> >> >> > >> > Lightbits Labs >> > Lead the cloud-native data center transformation by delivering scalable >> > and efficient software defined storage that is easy to consume. >> > >> > This message is sent in confidence for the addressee only. It may contain >> > legally privileged information. The contents are not to be disclosed to >> > anyone other than the addressee. Unauthorized recipients are requested to >> > preserve this confidentiality, advise the sender immediately of any error >> > in transmission and delete the email from their systems. >> > >> > >> > > Lightbits Labs > Lead the cloud-native data center transformation by delivering scalable and > efficient software defined storage that is easy to consume. > > This message is sent in confidence for the addressee only. It may contain > legally privileged information. The contents are not to be disclosed to > anyone other than the addressee. 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