On 19 April 2018 at 07:31, Mark Kirkwood <mark.kirkw...@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
