On May 30, 2013, at 5:25 AM, folkert wrote: > Hi, > > I'm going to setup a software raid-1 and would like to improve its > performance by storing things like the write intent bitmap (and fs > journals but that's not relevant here) on a seperate disk. In this case > and SSD. "mirror" segment type or "raid1" segment type? You can do this via device-mapper (i.e. 'dmsetup') for both target types. However, if you are using LVM, you can only have separate placement of the log device with the "mirror" segment type. > I was wondering: as SSDs frequently seem to die, what happens with the > raid? Things will probably oops, panic and crash but after the reboot: > will it refuse to come up? Or will it come up and just to a complete > resync? If you are using "mirror" segment type via LVM, it will simply convert to using an in-memory log. However, that means that the entire mirror will need to be sync'ed if you deactivate the LV or reboot the machine. (You could always replace the log on a different device though.) So, there are a few options, but I'd be interested to see if there is any real benefit to putting the log on an SSD. brassow -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
