Re: blending fast and temp space volumes

On Wed, Feb 21, 2018 at 4:50 PM, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> On Wed, Feb 21, 2018 at 7:53 AM, Rick Otten <rottenwindfish(at)gmail(dot)com> wrote:
>> side note: The disadvantage of local SSD is that it won't survive "hitting
>> the virtual power button" on an instance, nor can it migrate automatically
>> to other hardware. (We have to hit the power button to add memory/cpu to
>> the system, and sometimes the power button might get hit by accident.) This
>> is OK for temp space. I never have my database come up automatically on
>> boot, and I have scripted the entire setup of the temp space volume and data
>> structures. I can run that script before starting the database. I've done
>> some tests and it seems to work great. I don't mind rolling back any
>> transaction that might be in play during a power failure.
>
> It sounds like you're treating a temp_tablespaces tablespace as
> ephemeral, which IIRC can have problems that an ephemeral
> stats_temp_directory does not have.

For instance?

I've been doing that for years without issue. If you're careful to
restore the skeleton directory structure at server boot up, I haven't
had any issues.

On Wed, Feb 21, 2018 at 4:22 PM, Craig James <cjames(at)emolecules(dot)com> wrote:
>
> On Wed, Feb 21, 2018 at 7:53 AM, Rick Otten <rottenwindfish(at)gmail(dot)com>
>> I was wondering if there anyone had ideas for how to make that possible.
>> I don't think I want to add the SAN disk to the same LVM volume group as the
>> local disk, but maybe that would work, since I'm already building it with a
>> script anyhow ... Is LVM smart enough to optimize radically different disk
>> performances?
>
>
> Couldn't you configure both devices into a single 6T device via RAID0 using
> md?

That would probably perform as slow as the slowest disk.