https://bugzilla.novell.com/show_bug.cgi?id=461277
User teheo@novell.com added comment
https://bugzilla.novell.com/show_bug.cgi?id=461277#c34
--- Comment #34 from Tejun Heo
As a test I've been doing a similar rsysnc/restore from USB using a subset of the data I wanted to restore (2 directories, about 20GB each, all files between 500M and 4G in size). I set this up in a while true loop and it's been running overnight so far (rsync, remove, rsync, remove, repeat). It probably would have failed by now.
Nice.
What's different between now and the time my disks were reset is now I have the computer plugged into a UPS, so I'm not vulnerable to fluctuations in utility power (before everything: computer, monitor, speakers, printer, etc were plugged into daisy chained power strips).
I don't have any first hand experience with power source problem (the power source quality here is pretty good) but yeah I can imagine that. The only related experience I had was an EMI verification test done at a company developing an external RAID rig. It wasn't voltage fluctuation per-se. They inserted high frequency interference to power line which doesn't cause noticeable voltage fluctuation at the output side but does cause quite some amount of EMI inside the machine. Serial connection for information display and SATA signals were highly susceptible to them. Well, it's gigahertz signal running along a relatively long unshielded cable after all. Anyways, for the brief loss of power problem, in most cases it seems dependent on the specific power supply. I suspect it's about how much capacitance they have at the output side but my electrical knowledge is severely limited, so it's just a wild guess. Rated wattage really doesn't have much bearing on the issue. I test many drives in varied configurations and hotplugging a drive into a loaded power supply is always a good litmus test for such problems and for some unknown reason cheap noname 300w power supply I have is the best behaving one. Now that hotplugging is a common thing, I'm afraid many people is experiencing such issue. It's disturbing but I can't think of a good software way to work around it as transmission failures which aren't uncommon due to the high susceptibility to EMI and the brief power loss seem identical to the host. I hope some people test power supplies for things like this but it never seems to be the focus of benchmarking or verification.
So signs point to power. I'm going to let the loop run for about 24 hours, but I'm pretty confident that I won't see a problem, it's already run about long enough to restore all of my data twice.
Dunno about the quality of your power source but it might be a good idea to put half of the disks to a separate power supply just for safety. It's perfectly safe to use different power sources for the disk and the host. SATA signal lines don't actually connect to each other. Thanks. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.