Re: Checkpoint cost, looks like it is WAL/CRC - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Checkpoint cost, looks like it is WAL/CRC
Date
Msg-id 3317.1120710284@sss.pgh.pa.us
Whole thread Raw
In response to Re: Checkpoint cost, looks like it is WAL/CRC  (Bruno Wolff III <bruno@wolff.to>)
Responses Re: Checkpoint cost, looks like it is WAL/CRC  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-hackers
Bruno Wolff III <bruno@wolff.to> writes:
> Are you sure about that? That would probably be the normal case, but are
> you promised that the hardware will write all of the sectors of a block
> in order?

I don't think you can possibly assume that.  If the block crosses a
cylinder boundary then it's certainly an unsafe assumption, and even
within a cylinder (no seek required) I'm pretty sure that disk drives
have understood "write the next sector that passes under the heads"
for decades.
        regards, tom lane


pgsql-hackers by date:

Previous
From: Bruno Wolff III
Date:
Subject: Re: Checkpoint cost, looks like it is WAL/CRC
Next
From: Bruce Momjian
Date:
Subject: Re: Checkpoint cost, looks like it is WAL/CRC