> > ---------- Forwarded message ---------- > From: Shmuel Melamud <[email protected]> > Date: Wed, Jun 22, 2016 at 4:51 PM > Subject: [ovirt-devel] Storage in VDSM questions > To: devel <[email protected]> > > > Hi! > > I have a bunch of questions related to storage in VDSM. I would be happy > if anybody familiar with the subject can help me with them. > > 1. What is HSM? IRS? >
IRS = SPM HSM=non SPM host > 2. What is SDM? > SDM= Storage Domain Management A feature currently under development that provides alternate method to SPM to manage shared storage. > 3. What hsm.spmSchedule() method does? > Schedules a task to be executed as SPM (used to perform operation that alter the shared storage or data operations currently). > 4. What does domainMonitor.getHostId(vol_info.sd_id) method return? > I'd recomment to do some SANLock reading (see below). Basically, its the id the host uses to acquire locks on the shared storage. http://linux.die.net/man/8/sanlock http://old.ovirt.org/SANLock > > Storage domain > > 5. What is StorageDomainManifest? Why there are separate StorageDomain and > StorageDomainManifest classes? (And the same with Volume and > VolumeManifest.) > Those are changes made in order to share "SPM" related code with "SDM" related code (as not all of the code is relevant for both). alitke/nsoffer could share more information on the decisions behind adding those. > 6. What does sd_manifest.domain_lock(host_id) guard? Why do we need the > host_id parameter? > see answer to question 4. > 7. Why in HSM we are using vars.task.getSharedLock(STORAGE, sdUUID) > sometimes instead of domain lock? > The task lock (which uses the resource manager) is used to acquire in memory logical lock within the current host. Theoretical example- you wouldn't want to attempt to delete a domain while you create a volume on it. 8. What does sd_manifest.get_volume_artifacts(img_id, vol_id) return? > > Resource manager > > 9. What is ResourceManager? > Resource manager is basically a in memory lock manager in vdsm. > 10. What rmanager.acquireResource(image_res_ns, img_id, lockType) does? > What types of resources it may be used with? > Well, the best answer would be the simple one - its used to acquire a resource, you can specify a namespace and id, the lock will be taken on namespace_ID so basically you can acquire lock on the same id under different namespaces. > > Images and volumes > > 11. What methods dom.linkBCImage(imgPath, imgUUID) and > dom.unlinkBCImage(imgUUID) do? > Creates/Removes a symlink to a given image. > 12. What methods dom.activateVolumes(imgUUID, imgVolumes) and > dom.deactivateImage(imgUUID) do? > Can you be a bit more specific in the question? I don't have much to add over the method names. > > 13. What method dom.getVolumeLease(imgUUID, volUUID) does? > see related SANLock question before. > 14. What methods volume.prepare() and volume.teardown() do? > > Thanks in advance for your answers! > > Shmuel > > _______________________________________________ > Devel mailing list > [email protected] > http://lists.ovirt.org/mailman/listinfo/devel > >
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