[BBLISA] RE: storevault / netapp
Edward Ned Harvey
bblisa2 at nedharvey.com
Wed Feb 27 22:29:28 EST 2008
> It is absolutely not the case that hardware RAID has across the board
> risk of data corruption, with or without caching. Caching usually
> speed, as you say.
> Take a look at this article if you want to be scared about data
> even when using hardware RAID:
> Theoretically, ZFS has much better data integrity than other file
> systems /
> volume managers / RAID controllers because it checksums all data and
> metadata, all the time. Nothing else (that I know of) does this.
This is really interesting. I have noticed bit errors occasionally, and I
am unusually paranoid of such a thing. It's about 50x more common in my
personal experience, with optical media than magnetic. And almost never on
a healthy ethernet. I do checksum and validate things with almost obsessive
compulsion. Especially installation & backup images.
That being said, I didn't know ZFS checksums on the fly. I can only assume
this hurts performance, likewise if there's a lack of hardware caching, but
I also habitually use iozone to benchmark my raid systems. Typically dell
sata disks with caching raid 5 controller.
I haven't googled for iozone results on ZFS systems, but if anyone here has
any such results, I'd be interested in comparing.
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