I was on CFQ so I changed it to noop. The problem still persisted however. Do you have any other ideas?
On Thu, Jul 23, 2015 at 5:00 PM, Jeff Ferland <j...@tubularlabs.com> wrote: > Imbalanced disk use is ok in itself. It’s only saturated throughput that’s > harmful. RAID 0 does give more consistent throughput and balancing, but > that’s another story. > > As for your situation with SSD drive, you can probably tweak this by > changing the scheduler is set to noop, or read up on > https://www.kernel.org/doc/Documentation/block/deadline-iosched.txt for > the deadline scheduler (lower writes_starved value). If you’re one CFQ, > definitely ditch it. > > -Jeff > > On Jul 23, 2015, at 4:17 PM, Soerian Lieve <sli...@liveramp.com> wrote: > > I set up RAID0 after experiencing highly imbalanced disk usage with a JBOD > setup so my transaction logs are indeed on the same media as the sstables. > Is there any alternative to setting up RAID0 that doesn't have this issue? > > On Thu, Jul 23, 2015 at 4:03 PM, Jeff Ferland <j...@tubularlabs.com> wrote: > >> My immediate guess: your transaction logs are on the same media as your >> sstables and your OS prioritizes read requests. >> >> -Jeff >> >> > On Jul 23, 2015, at 2:51 PM, Soerian Lieve <sli...@liveramp.com> wrote: >> > >> > Hi, >> > >> > I am currently performing benchmarks on Cassandra. Independently from >> each other I am seeing ~100k writes/sec and ~50k reads/sec. When I read and >> write at the same time, writing drops down to ~1000 writes/sec and reading >> stays roughly the same. >> > >> > The heap used is the same as when only reading, as is the disk >> utilization. Replication factor is 3, consistency level on both reads and >> writes is ONE. Using Cassandra 2.1.6. All cassandra.yaml settings set up >> according to the Datastax guide. All nodes are running on SSDs. >> > >> > Any ideas what could cause this? >> > >> > Thanks, >> > Soerian >> >> > >
