Re: Re: TODO list

> > So, for what CRC could be used? To catch disk damages?
> > Disk has its own CRC for this.
> 
> Oh, I see.  For anyone else who has trouble reading between the lines:
> 
> Blocks that have recently been written, but failed to make it down to
> the disk platter intact, should be restorable from the WAL log.  So we
> do not need a block-level CRC to guard against partial writes.
> 
> A block-level CRC might be useful to guard against long-term data
> lossage, but Vadim thinks that the disk's own CRCs ought to be
> sufficient for that (and I can't say I disagree).
> 
> So the only real benefit of a block-level CRC would be to guard against
> bits dropped in transit from the disk surface to someplace else, ie,
> during read or during a "cp -r" type copy of the database to another
> location.  That's not a totally negligible risk, but is it worth the
> overhead of updating and checking block CRCs?  Seems dubious at best.

Agreed.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026