Search Results for: raid disk

Spreading .ibd files across multiple disks; the optimization that isn’t

Inspired by Baron’s earlier post, here is one I hear quite frequently – “If you enable innodb_file_per_table, each table is it’s own .ibd file.  You can then relocate the heavy hit tables to a different location and create symlinks to the original location.” There are a few things wrong with this advice:

The perils of uniform hardware and RAID auto-learn cycles

Last night a customer had an emergency in selected machines on a large cluster of quite uniform database servers. Some of the servers were slowing down in a very puzzling way over a short time span (a couple of hours). Queries were taking multiple seconds to execute instead of being practically instantaneous. But nothing seemed […]

RAID throughput on FusionIO

Along with maximal possible fsync/sec it is interesting how different software RAID modes affects throughput on FusionIO cards. In short conclusion, RAID10 modes really disappoint me, the detailed numbers to follow. To get numbers I run

test with 16KB page size, random read and writes, 1 and 16 threads, O_DIRECT mode. FusionIO cards are […]

RAID vs SSD vs FusionIO

In benchmarks passion (see my two previous posts) I managed to setup all three devices (RAID was on board; Intel X25-E SSD connected to HighPoint controller, FusionIO card) on our working horse Dell PowerEdge R900 (btw, to do that I had to switch from CentOS 5.2 to Ubuntu 8.10, as CentOS was not able to […]

RAID System performance surprises

Implementing MySQL database in 24/7 environments we typically hope for uniform component performance, or at least would like to be able to control it. Typically this is indeed the case, for example CPU will perform with same performance day and night (unless system management software decides to lower CPU frequency due to overheating). This is […]

How Innodb flushes data to the disk ?

In my previous post I was a bit wrong giving Innodb some properties it does not have. In fact Innodb does not currently sort pages in their position order flushing them to disk. Pages to be flushed are instead identified by other means – LRU and pages which contain oldest LSN (so which were flushed […]