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20040527: bigbird rises from the ashes :-)

>From: Gerry Creager N5JXS <address@hidden>
>Organization: Texas A&M University -- AATLT
>Keywords:  200405270011.i4R0BjtK010667 LDM Linux RAID JFS

Hi Gerry,

>I do not yet propose to rename it 'phoenix'...

I was going to recommend that you do if all goes well :-)  I just
watched Flight of the Phoenix again (tenth time?) the other night, so
this was on my mind.

re: chunk-size setup in /etc/raidtab

>I did find several web references recently that recommended 4k chunking. 
>I'd done larger chunks with the 'hardware' RAID, and we know the 
>results, although these were likely muddied by other issues.  I don't 
>mind re-chunking if you want to try it, and I'd be willing to go to 128k 
>for a test.

Well, bigbird is crusing right now, so it is hard to argue with the 4K
chunk-size:

-- tail end of ~ldm/logs/bigbird.uptime

20040527.1628   0.91  1.26  1.82    8   0   8   1970  49M    0  0 scourBYnumber
20040527.1629   0.56  1.10  1.73    8   0   8   1983  48M    0  0 scourBYnumber
20040527.1630   1.13  1.17  1.71    8   0   8   2010  50M    0  0 scourBYnumber
20040527.1631   2.07  1.49  1.80    8   0   8   2021  48M    0  0 scourBYnumber
20040527.1632   1.21  1.34  1.72    8   0   8   2056  49M    0  0 scourBYnumber
20040527.1633   0.83  1.24  1.66    8   0   8   2067  49M    0  0 scourBYnumber
20040527.1634   0.65  1.12  1.59    8   0   8   2082  48M    0  0 scourBYnumber
20040527.1635   0.88  1.12  1.56    8   0   8   2101  49M    0  0 scourBYnumber
20040527.1636   0.50  0.96  1.48    9   0   9   2123  48M    0  0 scourBYnumber
20040527.1637   1.11  1.08  1.49    8   0   8   2155  49M    0  0 scourBYnumber
20040527.1638   0.98  1.06  1.45    8   0   8   2184  48M    0  0 scourBYnumber
20040527.1639   0.96  1.04  1.42    8   0   8   2204  48M    0  0 scourBYnumber
20040527.1640   1.87  1.24  1.46    8   0   8   2228  49M    0  0 scourBYnumber
20040527.1641   1.74  1.35  1.49    8   0   8   2258  48M    0  0 scourBYnumber
20040527.1642   0.87  1.18  1.42    8   0   8   2280  49M    0  0 scourBYnumber
20040527.1643   0.76  1.08  1.37    8   0   8   2288  49M    0  0 scourBYnumber
20040527.1644   1.56  1.19  1.38    8   0   8   2315  49M    0  0 scourBYnumber

These are the lowest load averages I have ever seen on bigbird while
the LDM and decoders are running!

Curiosity:  was the setup error in raidtab specifying that there were
spare disks that weren't there?  I didn't study the differences between
raidtab and raidtab.old last night...

I am all for staying with this setup if it works well.  Again, I am
just trying to learn as much as possible about RAID on Linux.  More and
more Unidata sites are moving to Linux (and Linux clusters), and
installing RAIDs since disks are so cheap (too bad the same can't be
said for memory!).

By the way, my Google searches last night showed that O'Reilly has a
book out on Linux and RAIDs: Managing RAID on Linux.  I will be picking
up a copy of this tomorrow if it is the store, otherwise I will be
ordering it ASAP.

Cheers,

Tom
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