[DRBD-user] slow disk throughput (fwd)

Tom Brown wc-linbit.com at vmail.baremetal.com
Thu Jun 19 20:08:08 CEST 2008


On Thu, 19 Jun 2008, Lars Marowsky-Bree wrote:

> On 2008-06-17T12:37:06, Tom Brown <wc-linbit.com at vmail.baremetal.com> wrote:
>
>>     8.0.12 (api:86/proto:86)
>>     --------
>>     [...]
>>      * Two new config options no-disk-flushes and no-md-flushes to disable
>>        the use of io subsystem flushes and barrier BIOs.
>>     [...]
>
> The better and safer option towards higher performance is putting the
> metadata on a different spindle, or possibly even on an SSD drive.

OK. since this is being suggested on a storage related list, I'm going to 
ask... As far as I know, SSD's _suck_ for write access... unless the 
system doing the writing is aware of and optimized for the underlying 
storage... e.g. a log structured storage system. I looked into these for 
mail-queue storage, and even bought one (32 gig, SATA, 2.5") ... it's 
sitting here on my desk unused.

Please tell me I am wrong (and provide some details :). e.g. a reasonable 
dram based solution?

-Tom

> Having the metadata and data on the same spindle is going to cause a
> significant performance hit due to the AL.





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