On 19 April 2018 at 07:31, Mark Kirkwood <mark.kirkwood@catalyst.net.nz> wrote:
> On 19/04/18 00:45, Craig Ringer wrote:
>
>>
>> I guarantee you that when you create a 100GB EBS volume on AWS EC2,
>> you don't get 100GB of storage preallocated. AWS are probably pretty
>> good about not running out of backing store, though.
>>
>>
>
> Some db folks (used to anyway) advise dd'ing to your freshly attached
> devices on AWS (for performance mainly IIRC), but that would help prevent
> some failure scenarios for any thin provisioned storage (but probably really
> annoy the admins' thereof).
This still makes a lot of sense on AWS EBS, particularly when using a
volume created from a non-empty snapshot. Performance of S3-snapshot
based EBS volumes is spectacularly awful, since they're copy-on-read.
Reading the whole volume helps a lot.
--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services