I believe the Apache mailer does not allow attachments, or at least images as attachments. I could be wrong, but I think I saw that elsewhere.
If necessary, you can post the image somewhere (e.g. Google drive) and email out a link. -Gerald On Thu, Feb 21, 2019 at 10:27 AM Chen Luo <cl...@uci.edu> wrote: > I re-attached the image as follows. In case it still doesn't show up, the > average point lookup throughput of* SSD for LSM + Logging* is only around > *3-4k/s*. When a separate hard disk is used for logging, the average > point lookup throughput reaches *30k-40k/s*. > > [image: image.png] > > Best regards, > Chen Luo > > On Thu, Feb 21, 2019 at 10:01 AM abdullah alamoudi <bamou...@gmail.com> > wrote: > >> Thanks for sharing Chen, very interesting. >> >> The image doesn't show up for me. Not sure if it shows up for others? >> >> Cheers, >> Abdullah. >> >> On Wed, Feb 20, 2019 at 1:29 PM Chen Luo <cl...@uci.edu> wrote: >> >> > Hi Devs, >> > >> > Recently I've been running experiments with concurrent ingestions and >> > queries on SSDs. I'd like to share an important lesson from my >> experiments. >> > In short,* it is very important (from the performance perspective) to >> use >> > a separate disk for logging, even SSDs are good at random I/Os*. >> > >> > The following experiment illustrates this point. I was using YCSB with >> > 100GB base data (100M records, each has 1KB). During each experiment, >> there >> > was a constant data arrival process of 3600 records/s. I executed >> > concurrent point lookups (uniformly distributed) as much as possible >> using >> > 16 query threads (to saturate the disk). The page size was set to 4KB. >> The >> > experiments were performed on SSDs. The only difference is that one >> > experiment had a separate hard disk for logging, while the other used >> the >> > same SSD for both LSM and logging. The point lookup throughput over time >> > was plotted below. The negative impact of logging is huge! >> > >> > [image: image.png] >> > >> > The reason is that logging needs to frequently force disk writes (in >> this >> > experiment, the log flusher forces 70-80 times per second). Even though >> the >> > disk bandwidth used by the log flusher is small (4-5MB/s), the frequent >> > disk forces could seriously impact the overall disk throughput. If you >> have >> > a workload with concurrent data ingestion and queries, please DO >> consider >> > using a separate disk for logging to fully utilize the SSD bandwidth. >> > >> > Best regards, >> > Chen Luo >> > >> >
