One major advantage I see with this is with SSDs. SSDs can sustain multiple threads writing to them synchronously. If we have multiple journals going to same SSD we surely will have more parallelism and extract greater throughput.
@Andrey at Salesforce did few micro benchmarks simulating this behavior and we got better results. We are yet to tryout this particular patch though. On Sun, Nov 20, 2016 at 7:23 AM, Flavio Junqueira (JIRA) <j...@apache.org> wrote: > > [ https://issues.apache.org/jira/browse/BOOKKEEPER-963? > page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel& > focusedCommentId=15681315#comment-15681315 ] > > Flavio Junqueira commented on BOOKKEEPER-963: > --------------------------------------------- > > I'm missing a bit more motivation for this feature. We already allow > multiple ledger directories, so is it the case that you're bottlenecked on > the journal and you want to have multiple journals per bookie? Could you > elaborate a bit further on your motivation, the hardware you're targeting > and such? [~mmerli] > > > Allow to use multiple journals in bookie > > ---------------------------------------- > > > > Key: BOOKKEEPER-963 > > URL: https://issues.apache.org/ > jira/browse/BOOKKEEPER-963 > > Project: Bookkeeper > > Issue Type: Improvement > > Reporter: Matteo Merli > > Assignee: Matteo Merli > > Fix For: 4.5.0 > > > > > > By configuring multiple journals, we can take advantage of the IO of > multiple > > disks to increase the write throughput of a single bookie. > > Each journal will have its own journal and sync threads and writes will > be > > assigned to a particular journal by hashing on the ledger id. > > In addition to using multiple physical disks, there can improvements > even by > > using multiple journal on a single SSD device, because these disks can > handle > > well multiple concurrent writes in different blocks of the disk. > > > > -- > This message was sent by Atlassian JIRA > (v6.3.4#6332) > -- Jvrao --- First they ignore you, then they laugh at you, then they fight you, then you win. - Mahatma Gandhi
