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Date:      Thu, 23 May 2013 11:00:21 +0200
From:      Albert Shih <>
To:        Paul Kraus <>
Cc:        Ivailo Tanusheff <>, Liste FreeBSD <>
Subject:   Re: ZFS install on a partition
Message-ID:  <>
In-Reply-To: <>
References:  <> <> <>

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 Le 18/05/2013 ? 09:02:15-0400, Paul Kraus a écrit
> On May 18, 2013, at 3:21 AM, Ivailo Tanusheff
> <> wrote:
> > If you use HBA/JBOD then you will rely on the software RAID of the
> > ZFS system. Yes, this RAID is good, but unless you use SSD disks to
> > boost performance and a lot of RAM the hardware raid should be more
> > reliable and mush faster.
> 	Why will the hardware raid be more reliable ? While hardware raid is
> 	susceptible to uncorrectable errors from the physical drives
> 	(hardware raid controllers rely on the drives to report bad reads and
> 	writes), and the uncorrectable error rate for modern drives is such
> 	that with high capacity drives (1TB and over) you are almost certain
> 	to run into a couple over the operational life of the drive. 10^-14
> 	for cheap drives and 10^-15 for better drives, very occasionally I
> 	see a drive rated for 10^-16. Run the math and see how many TB worth
> 	of data you have to write and read (remember these failures are
> 	generally read failures with NO indication that a failure occurred,
> 	bad data is just returned to the system).
> 	In terms of performance HW raid is faster, generally due to the cache
> 	RAM built into the HW raid controller. ZFS makes good use of system,

Before I'm installing my server under 9.0 + ZFS I do some benchmarks with
ionice to compare 

    FreeBSD 9.0+ ZFS + 12 disk SATA 7200 rpm vs CentOS + H700 + 12 disk SAS 15krpm

(Both are same Dell poweredge).

And the ZFS+12 disk sata goes much faster than CentOS+H700+ext4 almost everywhere. Only
for small file AND small record size the ZFS is slower than CentOS. 

The server don't have SSD. He got 48Go of ram. 


Albert SHIH
DIO bâtiment 15
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5 Place Jules Janssen
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Heure local/Local time:
jeu 23 mai 2013 10:53:50 CEST

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