On Tue, Jan 14, 2014 at 1:25 AM, David Brown <david.brown@xxxxxxxxxxxx> wrote: > On 06/01/14 19:13, Mark Knecht wrote: >> Andrea, >> As others have said it looks interesting. Thanks for the efforts. >> >> Question: As an end-user type who currently uses mdadm RAID6, if I >> wanted to set up a dedicated machine to do some SnapRAID testing then >> what's the minimum disk hardware I'd need assuming Linux is just on >> it's own disk? >> >> 1) 1 drive for Linux >> 2) 4 (or possibly 3) drives for a SnapRAID RAID6 device? >> 3) 3 drives for a SnapRAID RAID5 device? (If RAID5 can even use >> SnapRAID. Not sure it can) >> >> Are there any known issues using both mdadm and SnapRAID devices in >> the same system? Again, I don't care if there are and the machine dies >> a brutal death (which I doubt from your announcement) but just asking. >> >> Cheers, >> Mark >> > > If you want to do testing (once there is mdadm support for making the > multi-raid devices), then an easy way is to make some big empty files on > an existing disk and set them up as loopback devices. Then you can use > these "fake" drives for the arrays. You can then test a 6+4 quad parity > array using 10 1G files rather than needing 10 physical drives, and you > can play with resyncing, fault testing (using the md "faulty" layout), > reshaping, etc. > > Of course, you can't test real-world speed this way. However, you /can/ > test parity generation/recovery speeds nicely by putting the loopback > files in a tmpfs system in memory - that eliminates the hard disk speeds > and lets you do hard testing of the raid code. > > Thanks David. I'll save this email and give it some thought. I've not used loopback devices before but some quick reading makes your suggestion seem quite interesting. Cheers, Mark -- 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
