Wednesday Jan 06, 2010

ZFS resliver performance improved!

I'm not being lucky with the Western Digital 1Tb disks in my home server.

That is to say I'm extremely pleased I have ZFS as both have now failed and in doing so corrupted data which ZFS has detected (although the users detected the problem first as the performance of the drive became so poor).One of the biggest irritations about replacing drives, apart from having to shut the system down as I don't have hot swap hardware is waiting for the pool to resliver. Previously this has taken in excess of 24 hours to do.

However yesterday's resilver was after I had upgraded to build 130 which has some improvements to the resilver code:


: pearson FSS 1 $; zpool status tank
  pool: tank
 state: ONLINE
status: The pool is formatted using an older on-disk format.  The pool can
        still be used, but some features are unavailable.
action: Upgrade the pool using 'zpool upgrade'.  Once this is done, the
        pool will no longer be accessible on older software versions.
 scrub: resilver completed after 6h28m with 0 errors on Wed Jan  6 02:04:17 2010
config:

        NAME           STATE     READ WRITE CKSUM
        tank           ONLINE       0     0     0
          mirror-0     ONLINE       0     0     0
            c21t0d0s7  ONLINE       0     0     0
            c20t1d0s7  ONLINE       0     0     0
          mirror-1     ONLINE       0     0     0
            c21t1d0    ONLINE       0     0     0  225G resilvered
            c20t0d0    ONLINE       0     0     0

errors: No known data errors
: pearson FSS 2 $; 
Only 6 ½ hours for 225G which while not close to the theoretical maximum is way better than 24 hours and the system was usable while this was going on.

Sunday Jan 07, 2007

DAB radio. Is it crap?

All weekend there has been no DAB radio reception in the house. It could be that my DAB radio is bust but we also have no UHF TV signal either and if I let the radio scan I do find some very strange stations with exceptionally poor signal strength. Yet nothing on the transmitter web site which was last updated on Friday (Last Updated 16:41 05/01/07) which was when things were working here. While writing this all has now returned so I now know it was not the multiple bits of equipment in the house I suspect the transmitter.

Being a geek I should love Digital Radio and conceptually I do. However where I live the signal is so bad it is just able to do voice radio but music is horrible where as FM is fine. It is not even as if I live in the sticks. I wonder if the government and the Radio authorities really live in the same country when they suggest that DAB can really compete with FM radio at this point. I can't see a DAB radio ever working in a car or more importantly on a bike. In the house my laptop and wifi gets better “radio” than DAB.

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This is the old blog of Chris Gerhard. It has mostly moved to http://chrisgerhard.wordpress.com

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