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Rushabh S Shah commented on HDFS-7928: -------------------------------------- This test fails on my system without the patch also. Also HDFS-7965 reports this. > Scanning blocks from disk during rolling upgrade startup takes a lot of time > if disks are busy > ---------------------------------------------------------------------------------------------- > > Key: HDFS-7928 > URL: https://issues.apache.org/jira/browse/HDFS-7928 > Project: Hadoop HDFS > Issue Type: Improvement > Components: datanode > Affects Versions: 2.6.0 > Reporter: Rushabh S Shah > Assignee: Rushabh S Shah > Attachments: HDFS-7928-v1.patch, HDFS-7928-v2.patch, HDFS-7928.patch > > > We observed this issue in rolling upgrade to 2.6.x on one of our cluster. > One of the disks was very busy and it took long time to scan that disk > compared to other disks. > Seeing the sar (System Activity Reporter) data we saw that the particular > disk was very busy performing IO operations. > Requesting for an improvement during datanode rolling upgrade. > During shutdown, we can persist the whole volume map on the disk and let the > datanode read that file and create the volume map during startup after > rolling upgrade. > This will not require the datanode process to scan all the disk and read the > block. > This will significantly improve the datanode startup time. -- This message was sent by Atlassian JIRA (v6.3.4#6332)