Re: High latency in metada write


Lombardi, Johann
 

Hi,

 

A DAOS update operation actually results in several sequential latency-sensitive operations over SCM to locate the object/dkey/akey (and create the associated trees if those don’t exist already) that you want to update. Once this is resolved, the 4K data buffer will be stored in either SCM or NVMe. DAOS uses SCM internally to accelerate the sequential metadata operations.

 

Cheers,

Johann

 

From: <daos@daos.groups.io> on behalf of "shadow_vector@..." <shadow_vector@...>
Reply-To: "daos@daos.groups.io" <daos@daos.groups.io>
Date: Wednesday 26 January 2022 at 03:26
To: "daos@daos.groups.io" <daos@daos.groups.io>
Subject: Re: [daos] High latency in metada write

 

Hi Johann:

Tansks for the information. I have checked the latency in the online documentation, about 12 us for update, much lower than that in my test. But I think SCM would be much faster while the 4K write latency is about 10us using NVMe. Does the SCM just resolve the WA problem?

Best Regards!

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