thus Ross Walker spake: > On Dec 9, 2009, at 8:05 AM, Timo Schoeler > <timo.schoeler at riscworks.net> wrote: > >> Hi list, >> >> during the last days there was a discussion going on about the >> stability >> of XFS; though I myself used XFS heavily and didn't run into issues >> yet, >> I'd like to ask something *before* we create our next generation data >> storage backend... >> >> Les Mikesell wrote in [0] about issues in the combination of XFS and >> LVM >> -- however, it was being discussed in context of using 32bit kernels. >> >> What I specifically need is to run XFS (or something similar, I am >> *not* >> forced to use XFS, but it was my preference for some years now, and I >> didn't have any issues with it yet) on top of LVM to be able to create >> snapshots. We're talking about several file systems of a size at about >> 4TiByte each. >> >> On another place [1] I read that there were issues with that. >> >> Can anyone shed some light on this? Would be very appreciated. > > There is no problem if it is done on x86_64 with it's 8k stack frames, > but on i386 with it's 4k stack frames you could run into a stack > overflow when doing it on top of stackable block devices (md raid, > lvm, drbd, etc). > > Also since the current LVM on CentOS doesn't support barriers (next > release I believe) journalling isn't safe on LVM unless you are using > a storage controller with BBU write-back cache. > > I have heard anyways that the current implementation of barriers isn't > very performant and doesn't take into consideration controllers with > BBU cache, so most people will end up mounting with nobarriers which > just means they are in the same boat as they are now. Better make sure > your machine is bullet proof as a power outage or a kernel panic can > spell disaster for XFS (or any other file system really). > > It is better to invest in a good hardware RAID controller until the > whole barriers stuff is ironed out. It should really perform better > then it does. Thanks for your detailed explanation, that really clears things up; however, I was intending to build a software RAID10 as we had really not so good experiences on hw RAID controllers int the past (for all kinds of phenomena). Would barriering here still be a problem then? Timo > -Ross