[Info-vax] RX2800 sporadic disk I/O slowdowns

[Lawrence D'Oliveiro]

On Sun, 20 Oct 2024 20:13:50 -0400, Arne Vajhøj wrote:

> On 10/20/2024 8:06 PM, Lawrence D'Oliveiro wrote:
>>
>> On Sun, 20 Oct 2024 19:08:41 -0400, Arne Vajhøj wrote:
>>>
>>> Let me try again.
>>>
>>> DB write to plates & system crash => OK but slow
>> 
>> The DB knows how to make this fast. Remember its cache is faster than
>> any disk controller.
> 
> This is where the DB is writing to plates.
> 
> You can add a fourth scenario:
> 
> DB write to DB cache & system crash => guaranteed problem with
> transaction

Transaction resilience is a standard thing with databases (and journalling 
filesystems) going back decades.

Some DBMSes don’t even want to work through filesystems, they would rather 
manage the raw storage themselves. This is why POSIX async I/O exists
<https://manpages.debian.org/7/aio.7.en.html>.