On Thu, 31 Oct 2002 23:29:57 -0700, "Andreas Dilger" <[EMAIL PROTECTED]> said: > When people were testing this with ext3 external journals, they just > used a RAMDISK for getting the performance measurements. Obviously, > (I hope ;-) this is not something you can do in real life, but for > performance measurement it is OK. > > Most people found that the ramdisk (and presumably the NVRAM device too) > didn't perform much, if any, better than having a separate fast disk for > the journal, because you are doing sequential I/O to the journal anyways. <...>
Yes, I'd heard something like this. Our servers aren't going to have a spare drive bay, I think, so a PCI NVRAM card may turn out to be a more economical solution (although I haven't received quotes back from the vendors yet...). If I do find a spare drive bay, how unsafe would it be to use a single drive, rather than RAID 1 mirroring? What does ReiserFS do if it gets an IO error on the journal device? Could that bring down our whole system? I assume that it would--in which case using NVRAM would actually save two drive bays, since it should be reliable enough to not need redundency. So, how big is a ReiserFS journal when using data=journal anyways?...
