Hi, I have only a little technical insight into this topic, however, I have some (terrible) personal experience with USB raid and I would point out another aspect. Although USBs are good for occasional connections of simple drives they have quite a strong tendency to wear out. This becomes a problem especially if you plan to connect raid often and means that wires might not connect or lose connection during the transition of data. I happened to have raid connected to older USB ports and connection was pretty unstable. Multiple times unexpected disconnection due to wires losing contact caused a problem and the disconnected disk (although almost perfectly valid) had to be completely rebuilt. I thought it was not that bad but later it caused sort of desync and I was unable to connect any two of three disks so the data was lost. My only luck was that I had all the data (at least important data) backed up. So if you're considering raid over USB I suggest you don't do that. It will probably save you a lot of troubles. With kind regards, 2018-01-23 21:46 GMT+01:00 Wol's lists <antlists@xxxxxxxxxxxxxxx>: > On 23/01/18 20:16, Linus Lüssing wrote: >> >> Hi, >> >> By chance I found this statement in the Linux RAID Wiki: >> >> "Do NOT use [USB devices] as part of your array. They have >> a timeout/disconnect mechanism which interacts very >> badly with the raid code." [0] > > > That was me that wrote that on the wiki. However, I'm just editing stuff so > I don't actually have any experience of it. >> >> >> Could someone elaborate further on this? Does "interacts very >> badly" mean that there will be potential data loss / data >> corruption? Or does "very badly" just mean short, temporary >> performance issues / lags upon a disk failure? >> > The wiki also mentions the timeout problem. As far as I can make out - and > bear in mind as I said above I don't have personal experience - it seems to > me from what I've picked up that USB suffers this problem in spades. > > In other words, what I *think* happens, from what I've picked up, is that > the USB bus times out. And when the raid comes along to use the disk, the > USB bus is no longer responding ... BOOM! > >> Regards, Linus >> > I hope that's helpful, and maybe people who know more will chime in, but > that's it as I understand it. > > Cheers, > Wol > > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Pokud tento mail obsahuje tautologii, pak zřejmě tautologii skutečně obsahuje. Vojtěch Kletečka -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
