On 05/07/16 12:07 +0300, Shmuel Melamud wrote:

Hi!

I'm writing code for a new verb (sparsifyInplace) in VDSM and got two different opinions about whether to use SPM or SDM for it:

1) SDM is the new correct approach, need to use it.

2) SDM is on early stage and may be changed significantly, so it is better to use SPM as mature and reliable approach.

What's your opinion?

SDM is definitely the better way to go, if you can, since it will make less work for you in the future and also make your verb use host resources more efficiently. My guess is that sparsifyInplace just needs to run a command against a volume path that is visible to a selected vdsm host and wait for it to complete. Do you intend for this to be run also while a VM is using the volume? For SDM verbs in vdsm there is a basic formula. All verbs are asynchronous. A new public API function is created in HSM. This function unpacks parameters and then creates and schedules a HostJob instance. The HostJob performs any necessary locking and does the work. It also has an interface for progress reporting and for aborting the operation. Engine monitors HostJobs using a public vdsm API. While it's true that SDM is in early stages, the underlying infrastructure that you will need has been upstream for awhile now. I'll be happy to provide some additional details if you have further questions. -- Adam Litke