tanvipenumudy commented on code in PR #7550: URL: https://github.com/apache/ozone/pull/7550#discussion_r2136262100
########## hadoop-hdds/docs/content/design/preallocate-blocks/preallocate-blocks.md: ########## @@ -0,0 +1,124 @@ +--- +title: PreAllocate and Cache Blocks in OM +summary: Prefetch blocks from SCM asynchronously and cache them within OM to reduce dependency on SCM for every write. +date: 2025-04-30 +jira: HDDS-11894 +status: draft +--- +<!-- + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + http://www.apache.org/licenses/LICENSE-2.0 + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. See accompanying LICENSE file. +--> + +## Introduction + +Whenever a write operation occurs, OM calls into SCM for allocateBlock. This adds overhead to each create request, including added latency to reach the create and allocateBlock request, as well as resource starvation since the thread in OM is blocked for the duration SCM responds to the call. + +Frequent RPC calls to SCM can become a performance bottleneck under heavy workloads. To address this, what if we could prefetch (preallocate) blocks from SCM asynchronously and cache them within OM to reduce this dependency on SCM? + +This design proposes a mechanism to preallocate blocks in OM and cache them for future use. This will reduce the number of network RPC calls to SCM and improve the overall performance of writes. + +#### Current Write Flow + + +#### New Write Flow + Review Comment: Thank you, swapped the names! -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@ozone.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@ozone.apache.org For additional commands, e-mail: issues-h...@ozone.apache.org
