On Mon, 24 Sep 2001, Nicholas Knight wrote: > > Turn it off (I have no idea of internals, but I presume it'll still > > be a write-through cache, so reading back will still be served from > > the buffer). Do hdparm -W0 /dev/hd[a-h]. > > I'm sorry, but that's not acceptable. > Please note the dd timings at the bottom of this message.
Well, of course, turning off the cache will cause performance penalties, but it at least gives you a chance to get away with a recoverable file system should the power fail or the box crash. > Yes, a typical desktop user isn't going to notice much, even a normal > webserver or fileserver not dealing with constant updates may not, but > certain workloads will. These workloads are real enough that telling > people to disable write caching out of hand is a bad idea. I switched a box to ext3 with write caches off in expectance of multiple power outages during works, and NOTHING happened. I expect that box is now writing 4 times slower than before, I have no real figures, and it's still "smooth enough" in spite of 2.4.9. > Keep in mind also, that you may be putting your data and filesystems in > more risk by not using a write cache as with using it. Utterly non-sense. Linear writing as dd mostly does is BTW something which should never be affected by write caches. -- Matthias Andree "Those who give up essential liberties for temporary safety deserve neither liberty nor safety." - Benjamin Franklin
