韓家標 Bill Hacker wrote: > Ivan Voras wrote: >> On 07/11/2007, Arne Wörner <arne_woerner_at_yahoo.com> wrote: >>> Maybe gjournal could help, because graid5 honors the BIO_FLUSH, but >>> that is >>> untested... >> >> Yes, AFAIK this would work. >> > > A RAID5 is one of the harder ones to do both fast and well in > software-only. > > The better hardware ($$$) controllers have fast hardware XOR engines as > well as CPU-as-state-machines and battery-backed cache, and THEY have to > work hard. I agree. But regarding the immediate topic of gjournal on graid5: gjournal has hooks in the UFS code to do full sync before journal switch (commit), which it then propagates to the devices and issues BIO_FLUSH, so it can offer both speed and reliability in this particular case. > Given decent hardware & any UPS that costs less than the hardware > controller, these are 'choices' - not really show-stoppers. In theory this is correct, in practice still many people don't know the choices they are implicitly making.Received on Wed Nov 07 2007 - 12:21:06 UTC
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