Toshiba disk low performance

[Christos Chatzaras]

I run these benchmark tests in Linux which show slow random writes. I don't think the issue is related to FreeBSD.



> On 8 Jun 2018, at 17:02, Daniel Feenberg <feenberg at nber.org> wrote:
> 
> 
> 
> On Fri, 8 Jun 2018, Christos Chatzaras wrote:
> 
>> I did some benchmarks and the problem exist in both Linux and FreeBSD.
>> 
>> I benchmark a server with Toshiba disks and a server with Seagate disks.
>> 
>> First I install debian without RAID-1. Then I install iozone.
>> 
>> Tests done with hdparm to test disk bandwidth and iozone to test random read/writes.
>> 
>> Here are the results:
>> 
>> https://hastebin.com/gayidosaju.pas
>> 
>> As you can see the bandwidth for the Toshiba disks is slower than Seagate but this doesn't really matter.
>> 
>> The problem is the second test that does random read/writes which show the Toshiba has 10 times slower random write speed than the Seagate.
>> 
>> That's why the issue happens mostly during a "mysql import" and not other server tasks.
> 
> Assuming that Smartdisk doesn't show a problem, don't you think that for some good or bad reason, the writes to the Seagate are async and writes to the Toshiba are sync? Perhaps FreeBSD has some rules about the default that Toshiba triggers in a different way than Seagate?
> 
> Daniel Feenberg
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