So in my previous post I showed some benchmarks showing a large drop off in performance when you fill the x-25e. I wanted to followup and say this: even if you do everything correctly ( i.e. leave 50%+ space free, disable controller cache etc ) you may still see a drop in performance if your workload is heavily write skewed.  To show this I ran a 100% random read sysbench fileio test over a 12GB dataset (37.5% full ) , the tests were run back-to-back over a several hours , here is what we see:

*Note the scale is a little skewed here ( i start at 2500 reqs ).

Each data point represents 2 million IO’s, so somewhere after about 6 million IO’s we start to drop.  At the end it looks like we stabilize around2900-3000 requests per second, an overall drop of about 25%.

The plan was only to do two quick posts on RAID Performance on the X-25e, but this was compelling enough to post on it’s own.  So in part I Mark Callaghan asked hey what gives with  the SLC Intel’s single drive random write performance,  It’s  lower then the MLC drive.   To be completely honest with you I had overlooked it, after all I was focusing on RAID performance.  This was  my mistake because this is actually caused by one of the Achilles heals of most flash on the market today, crappy performance when you fill more of the drive.  I don’t really know what the official title for it is but I will call it “Drive Overeating”.

Let me try and put this simply:  a quick trick most vendors use to push better random write #’s and help wear leveling is to not …

Everyone loves SSD.  It’s a hot topic all around the MySQL community with vendors lining up all kinds of new solutions to attack the “disk io”  problem that has plagued us all for years and years.  At this year’s user conference I talked about SSD’s and MySQL.   Those who follow my blog know I love IO and I love to benchmark anything that can help overcome IO issues.  One of the most exciting things out their at this point are the Intel x-25e drives.  These bad boys are not only fast but relatively inexpensive.  How fast are they?  Let’s just do a quick bit of review here and peak at the single drive #’s from sysbench.    Here you can see that a single X25-e outperforms all my other single drive test.

Yep you have probably seen this type of chart on other sites…   The great thing about the Intel drives is their performance on writes, this difference gives …

Javier Soltero, former CEO of Hyperic, has maintained that the sale of Hyperic to SpringSource was driven by discussion between himself and SpringSource CEO, Rod Johnson, but the fact that the companies shared investors - Accel Partners and Benchmark Capital - no doubt accelerated the deal (and I wonder whether either could have afforded to acquire the other without shared investors).

When examining the open source vendor landscape it is tempting to imagine that the combined total could be bigger than the sum of its parts - that a combination of many open source product specialists could mount a challenge to Red Hat and Sun to claim the title of biggest open source software vendor.

Benchmark and Accel are among …

Pre-UC I put out a teaser on some dbt2 scores in the 50K range.   I mentioned and showed the graphs during my SSD session, but I thought I would show them here for those who skipped the UC or did not attend my session.  Basically what most people consider to be a classic “CPU Bound” workload where all of your data easily fits into memory can also see benefits from moving to SSD’s. Remember just because everything fits into memory doesn’t mean your not going to be doing some operations to disk ( logging, flushes, etc ). Take a look:

Well I just finished my SSD session.  I was concerned by the amount of slides I had so I  kept trimming them back.  What happened?  I finished early.  Why?  The problem with storage is it’s not really that sexy.  I mean nobody ( sane anyways ) drools over drive specs ( I do consider myself insane by the way , and do drool over some drives ).   CPU’s are sexy…  memory…  sexy …  graphics cards sexy…  drives…  are not.  We only had a small crowd turn out (50-60 people maybe), but they were vocal and interactive.  I got some great feedback from others who love IO performance as much as me.   In fact one antendee stopped me in the hall and thanked me , telling me I helped him make up his mind to purcahse some SSD drives,  which made it worthwhile.

Take a look here:

  Response Time (s)
 Transaction      %    Average :    90th %        Total        Rollbacks      %
------------  -----  ---------------------  -----------  ---------------  -----
    Delivery   3.98      0.211 :     0.266       274829                0   0.00
   New Order  44.78      0.157 :     0.187      3090951            30925   1.00
Order Status   3.99      0.149 :     0.179       275357                0   0.00
     Payment  42.76      0.150 :     0.180      2951361                0   0.00
 Stock Level   3.99      0.152 :     0.182       275564            92070  33.41

50606.82 new-order transactions per minute (NOTPM)
60.5 minute duration
0 total unknown errors
31 second(s) ramping up

If you know what this output is from, and you know what 50K TPM means… your probably curious about these #’s. I am probably tantalizing you right now in fact. But I am not going to tell you more, not yet. So go ahead and guess. Better yet come …

I am doing the final prep work for my upcoming UC presentation on SSD’s, and I thought I would throw this out their. Recently their has been a great deal of discussion on the write cache on the Intel x-25e and whether you need to disable it to prevent data loss on a power outage. Most disk caches are not protected by a battery backup and are disabled by default on most high end controllers. Who wants to potentially lose 16-64MB of data on an outage? So it seems like it would make sense that you should disable the cache on the Intel drives as well. But their is a problem. Vadim over at the MySQL Performance Blog recently published some benchmarks that show some rather slow results when the disk cache is disabled, in fact I have also noticed a significant slow down in these cases as well. So this leads to the …

I have been benchmarking Waffle Grid using the new Innodb Plugin 1.03 the past couple of days. Let me say the plugin is fast. Which got me thinking, generally when you fix a bottleneck another area becomes a bottleneck… its a vicious cycle really. I figured why not benchmarks several different settings just to see what sort of improvement or detriment we get in Inno. This hopefully will lead to the next place to look for potential performance improvements. For the test I chose a somewhat IO bound setup and a CPU bound setup.

The IO bound setup was a 20W test, 768M buffer pool.
The CPU boud setup was a 20W test, 5GB buffer pool.

I decided to start with the Double Write Buffer. For those who are not familiar with the double write buffer check out the docs or …