-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Bruce Momjian wrote: > Matthew Wakeling wrote: >> On Fri, 13 Nov 2009, Greg Smith wrote: >>> In order for a drive to work reliably for database use such as for >>> PostgreSQL, it cannot have a volatile write cache. You either need a write >>> cache with a battery backup (and a UPS doesn't count), or to turn the cache >>> off. The SSD performance figures you've been looking at are with the drive's >>> write cache turned on, which means they're completely fictitious and >>> exaggerated upwards for your purposes. In the real world, that will result >>> in database corruption after a crash one day. >> Seagate are claiming to be on the ball with this one. >> >> http://www.theregister.co.uk/2009/12/08/seagate_pulsar_ssd/ > > I have updated our documentation to mention that even SSD drives often > have volatile write-back caches. Patch attached and applied. Hmmm. That got me thinking: consider ZFS and HDD with volatile cache. Do the characteristics of ZFS avoid this issue entirely? - -- Dan Langille BSDCan - The Technical BSD Conference : http://www.bsdcan.org/ PGCon - The PostgreSQL Conference: http://www.pgcon.org/ -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkuAayQACgkQCgsXFM/7nTyMggCgnZUbVzldxjp/nPo8EL1Nq6uG 6+IAoNGIB9x8/mwUQidjM9nnAADRbr9j =3RJi -----END PGP SIGNATURE----- -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
