ZAR RAID5 recovery

[Donnie]

I lost a RAID5 array due to a faulty power connector on one drive and a loose SATA cable on another. Long story short I've got a corrupted array. While figuring out cable problems I also lost what order the drives were connected in.

Because of the size of my array (1.2TB) it's taking quite some time to scan the array. After 25 hours it's at 27% done pass #1 of ZAR's "Numerical computation". Running with an Opteron 185 w/2GB DDR550. ZAR reports 95-105% cpu. I presume ZAR is not multi-core aware and/or not a multi-threaded process as XP reports 48-52% CPU usage by ZAR.

My first question is how many passes does the numerical computation take and what comes next that I could estimate how long this will take. At 1% per hour average this step alone is going to take another 73 hours and my wife wants to know when her digital photos are going to be back.

And my second question is would a multi-cpu/core aware ZAR be of any benefit to anyone, especially when dealing with large disks/arrays such as mine?

Donnie

[Alexey V. Gubin]

There are two passes in RAID computation. Second pass should be faster than a first one unless something unusual happens.

Regardless of the result of the scan, make sure you rename the log file
C:\Program Files\ZAR\logfile.txt
to something else, like
C:\Program Files\ZAR\saved logfile.txt
immediately after ZAR exits, i.e. before you start ZAR for a second time.

CPU usage in the status bar is indicated relative to one CPU. So it is possible to get more than 100% on a dual processor machine.

The implementation of a multiprocessor-aware numerical processing is planned, but not that soon (I think this will be no earlier than in 8.4). There are some problems with this since the particluar math does not parallelize that well.