… lot have been written about Battery Learning Cycle problems and its impact to MySQL Performance. Here are… ———————————————————————- Logical device number 0 Logical device name : RAID10-A RAID level : 10 Status of logical device : Optimal Size : 571382 …
Post: Battery Learning still problem many years after
February 10, 2011 By 7 Comments
The performance problems caused by battery auto learning go many years back. We wrote about it, other people … Dell product line ? (Which is using LSI chips) Are there RAID controllers which do not have this problem ? For many installations… write back even with no battery which will likely trash your database if power goes down during learning process. It may be…
Post: RAID System performance surprises
March 5, 2008 By 7 Comments
… be aware of couple of things Battery Learning and Charging Build in Battery has to pass through learning cycle every 3 months or so and this cycle takes about 7 hours according to the docs. During this time battery… investor show case or other important event. Learn what cron jobs does your RAID card have and see how they can be…
Post: The perils of uniform hardware and RAID auto-learn cycles
November 16, 2010 By 16 Comments
… the customer to check the RAID controller quickly on one of the failing machines. The result: the battery-backed cache was in…. Same thing — write-through, battery charging. And the battery backup unit was set to run through auto-learn cycles periodically, which is generally… file and found the command we needed to disable auto-learn, (++text files and saving links to reference material), sent that…
Post: Reasons for MySQL Replication Lag
July 29, 2011 By 6 Comments
… may cause the problem. Many RAID controllers have to periodically go through battery learning cycle which switches RAID cache in write-through mode which… be you running backup through xtrabackup or LVM snapshot, RAID controller doing RAID validation, some centrally kicked of SAN backup, intensive activity…
Post: More on dangers of the caches
September 23, 2010 By 5 Comments
… in search engine bot activity. It may be RAID writeback cache disabled due to battery learning but there must be something. This is… can serve all traffic without problems. So what we can learn from this, besides cache design related issues I mentioned in…
Comment: RAID System performance surprises
March 5, 2008 By 7 Comments
… the command which tells when next Learn cycle to be: [root@DB01 ~]# omreport storage battery controller=0 Battery 0 on Controller PERC 5… : Battery 0 State : Ready Recharge Count : Not Applicable Max Recharge Count : Not Applicable Predicted Capacity Status : Ready Learn State : Idle Next Learn Time… instead: http://www.lsi.com/storage_home/products_home/internal_raid/megaraid_sas/megaraid_sas_8408e/index.html?remote=1
Post: Evaluating IO subsystem performance for MySQL Needs
March 5, 2008 By 23 Comments
… I’m testing this on has 256MB BBU (Battery Backed up Cache) on RAID controller so we will test two workloads size… cached reads because they may show latency to the RAID cache if RAID read cache is enabled. If it is disabled you… especially playing with data size a bit you will well learn how your cache behaves. Were even more so interested about…
Post: How much overhead DRDB could cause ?
June 2, 2008 By 4 Comments
… the same time you must have BBU (Battery backed up unit) on your hardware RAID card or something which has same effect, especially as it become pretty cheap these days. With good RAID as I benchmarked you can be getting over 10000 req… lesson – do not take the overhead as a number but learn where this overhead comes from so you can find how…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
… of information on the box’s hardware, including RAID controllers, installed memory, and so on in the…I can also get information about the all-important battery-backed write cache, how it’s configured and … every option in the file. But again, you learn quickly if something strange is here. This whole…
