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Re: Pathological RAIDframe rebuild times

I've seen something similar.  Identical hardware with widely varying
rebuild times (2 hours vs 12 hours for 2x500GB RAID-1).  I just
assumed I had gone crazy and misremembered the old rebuild times :).

In my case these were "new" installs (drives not pre-zeroed) with the
rebuild ran from the install USB pre-install.  So the fact my drive
weren't zeroed might have been the cause.


On Fri, Apr 8, 2011 at 3:33 AM, Stephen Borrill 
<> wrote:
> I've a couple of HP Microservers, both with 4x WD Caviar Green 2TB drives.
> Operating system (netbsd-5) is on USB (same image used on both). Drive write
> caches are enabled in the BIOS and also double-checked with dkctl.
> I'm attempting to create a RAID5 array, stripe is 32 and partitions start at
> 0 sectors. I've tried both 3 and 4 disk arrays (understanding the preference
> for 3 disks ones as discussed in earlier threads).
> All drives have had a full dd of /dev/zero over them before starting (hit
> lots of bad sectors out of the box on this model of drive).
> On one server, the build took around 12 hours (which is similar to seen in
> the past). On the second, it estimated around 120. After a bit of playing
> around (nothing specific, just starting and stopping, changing from 4 to 3
> disks, double-checking BIOS settings), a new build said 12 hours. But after
> about 10% it ramped up to 120hours again.
> tps on the disks is around 200. Transfer rate (according to systat iostat)
> is around 3.5 MBps. Interrupt rates are around 650/s.
> The drives are doing little: a simultaneous dd read gives around 65MBps
> (compared to double that for the spare drive).
> --
> Stephen

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