…maybe just normal. We didn’t try too hard to get better performance because we already had…. Since starting a snapshot take less than a second, you could even be more zealous. Pretty interesting…other drive in the mirror. Better availability and disk usage On purpose, I allocated mirror pairs using…
Post: Aligning IO on a hard disk RAID – the Theory
June 9, 2011 By 18 Comments
… had were rotating hard disk drives. I think the reason is very simple – when systems only had one bearing hard disk drive (HDD) as… a single disk because of the alignment to a stripe unit. In the second example however every other page spans two disks so… decide on very early when configuring RAID. Disk sectors Most if not all hard disk drives available on the market these days use…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 13 Comments
… ========== ==== ======= ====== ======= ============ =========== Hard Disk SAS Online 0/0/0 SEAGATE ST3600057SS 558.911 Hard Disk SAS Online 0/0/0 SEAGATE ST3600057SS 558.911 Hard Disk … OS buffers. Buffers would be flushed within first few seconds so the effects of this were marginal. Alexey Kopytov…
Post: How multiple disks can benefit for single client workload ?
April 26, 2008 By 4 Comments
… of the article lets comment on IO vs Disk question. If you look at Disk Based databases all data accesses are treated… for it. If we take 15K RPM Hard Drive it does 250 rotations per second (4ms per rotation) which gives us 2ms… not be able to get over 30-50% from the second hard drive (and diminishing returns if you keep more copies). So…
Post: Is disk Everything for MySQL Performance ?
April 25, 2008 By 7 Comments
… always the case. There are whole classes of systems where Disk performance is not that important – consider for example systems where… IO capacity in spindles – So your hard drive can do 200 random reads per second and your SSD drive can do 10000 does it mean if you have array with 50 hard drives it…
Comment: InnoDB Flushing: a lot of memory and slow disk
April 1, 2011 By 57 Comments
… it comes to rotating disks. For blocks physically close to each other, head move isn’t necessary, the hard drive only has… whole hard disk, and run the same benchmark again on a small partition at the beginning of the disk. The number of the second… with a sequential io benchmark too, the beginning of the disk will be always faster, you can see “steps pattern” when…
Comment: InnoDB Flushing: a lot of memory and slow disk
March 31, 2011 By 57 Comments
… it comes to rotating disks. For blocks physically close to each other, head move isn’t necessary, the hard drive only has… whole hard disk, and run the same benchmark again on a small partition at the beginning of the disk. The number of the second… with a sequential io benchmark too, the beginning of the disk will be always faster, you can see “steps pattern” when…
Post: Mail clients and Databases
March 13, 2007 By 14 Comments
… store it for long time if not forever. With modern hard disk sizes it should not be problem at all, but because… these systems. Second one is crash recovery – in case of corruption due to power down or lack of disk space I see…
Comment: How reliable RAID really is
July 2, 2006 By 13 Comments
… data is lower, even though it also can fail loosing second hard drive, if they come from the same stripe. Meaning you… would. It however failed due to bad block on the second drive. In general the point is there is data of… it is good to have data on RAID10 with spare disk, have reduntant servers and of course backup which you can…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
…, which is a worst-case scenario for spinning disks. This is also very hard to prove, but seems reasonable based on the… units of operations per second. Given our assumed correlation between a Key_read and a random physical disk I/O, it is… ten seconds, so we can assume Key_reads are causing about ten random I/Os per second. Compare that to what your disks…
