… I have repeated it with (a) write-through and (b) write-back to see if write-back cache would minimize the effects of… twice – first with RAID controller cache set to Write-Through and then to Write-Back. 1. Baseline – misalignment on the partition table…% — 909 iops unaligned -vs- 1049 aligned. Random write. This is an important metric for write intensive workloads where there’s a lot of…
Post: Death match! EBS versus SSD price, performance, and QoS
February 21, 2011 By 55 Comments
… be 100% utilized until average read concurrency reached 6 and write concurrency reached 3. One of the samples shows the performance…-millisecond latencies to disk, pretty much consistently, for reads and writes, is very good. I’m averaging across large periods of… well if the database fits in memory and isn’t write-intensive. But the high and unpredictable latency of EBS storage means…
Comment: Linux schedulers in tpcc like benchmark
January 31, 2009 By 19 Comments
… queues size/depths); indeed scheduling is not only about aggregating write requests and bulk performances, but also about arbitrating resources usage… suspect a mixed workload (alternated write intensives, reads, and cpu bound moments, not just huge sustained writes) would give controller better chances to…
Comment: Tokyo Tyrant - The Extras Part I : Is it Durable?
August 20, 2010 By 5 Comments
… tunable fillfactor) the table itself can be tuned so that write hotspots – in conjunction with any striped RAID – are more likely… times of the day/month/year for the a write-intensive periods of heavy writes to flush its dirty pages quickly & regularly in… pace of the IO controller’s ability to safely perform writes. This requires understanding what parameters to set in sysctl, but…
Post: Master-Master or Master with Many Slaves
April 6, 2007 By 7 Comments
… simple things mean less software bugs. Handling write load If your application is write intensive master-N-slave configuration will be saturated much faster because it has to handle much more write load. Especially…
Post: FlashCache: tpcc workload with FusionIO card as cache
June 2, 2010 By 20 Comments
… for FlashCache usage ( as there high write rate on FlashCache for both reading and writing to/from disks, so lifetime could be… on FusionIO in 20% dirty page, 80% dirty pages and write-through modes. I used full 80GB for caching ( total size… to RAID). Write-through mode is about 2x gain, but remember that load is very write intensive and all benefits in write-through mode…
Comment: Master-Master or Master with Many Slaves
April 7, 2007 By 7 Comments
… dealing with master promotion design here. “Handling write load If your application is write intensive master-N-slave configuration will be saturated much faster because it has to handle much more write load. Especially…
Post: When would you use SAN with MySQL ?
March 9, 2009 By 18 Comments
… processing (and extra trip) involved. This in particular hurts log writes which are very latency critical. Now what is about MySQL… MySQL if you’re looking for durable transactions the log write latency is triple important compared to other database systems. MySQL… number of outstanding request significantly. For write intensive workload you will have problem with number of outstanding writes too. Though for that we…
Comment: How much overhead DRDB could cause ?
June 3, 2008 By 4 Comments
… about 3ms latency for a small (one sector, 512 bytes) write request. Consider further that with Gigabit Ethernet, we get about…), your local I/O latency decreases dramatically. Now your local writes “complete” in something like .1 to .3ms. So in relation… your application is highly write intensive, you’ll probably not notice much of this. However, for extremely high write loads, DRBD currently does…
Comment: Looking on 5.4 - IO bound benchmarks
May 1, 2009 By 5 Comments
… ensure the runs we publish have enough run time to write (cycle through) log files 3x or so – this also would… “In memory” here – because there are log writes and dirty page flushes from writes there is no guaranty the disk will not… means CPU bound but it is not always so for write intensive.
