On Mon, 26 Jun 2017, FERNANDO FREDIANI wrote: > Hello folks. > > I have been using Bcache in a server in production with pretty good results so > far. > > Now I am looking to add it also to another server that is suffering from disk > I/O. However this server in question has a fairly large storage running (circa > 8TB of used data) and therefore stopping it for a long period becomes > difficult. > > Question is: Can I add an SSD and Bcache to this server and use it for the > existing 8TB filesystem ? If so when I run make-bcache -B /dev/sdx1 to create > the backing device will it not overwrite what is currently on /dev/sdx1 ? Not officially. The bcache superblock is in the first 8k of disk (by default, but can align the payload) so 8TB would need shifted right assuming the right-hand-side has room to grow. Disclaimer: this could be dangerous, so at your own risk: While I've not tried this, theoretically you could put dm-linear atop of the bcache bdev and prepend some metadata area, using the `--data-offset` parameter in make-bcache as the start of your data area. Be sure to test on something non-critical if you go this route and make sure the sector math is correct or risk damaging the front of your 8TB volume. If you go this route and it works, please report back with what you did! -- Eric Wheeler > > Thanks > Fernando > -- > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
