Seth Mos wrote:
> At 15:00 2-8-2001 -0600, Steve Wolfe wrote:
> > > >I assume you mean software RAID5, right? I've got a RAID50 array:
> > > >28-port
> > > >3ware cards in hw raid5, then those two devices combined softwareraid0.
> > > >I
> > > >didn't bother to make the log on a separate device, but I could,
> > ifneed be.
> > >
> > > That is silly. Just make a big raid0 of it. If for some reason one ofthe
> > > 3ware cards takes a dump you WILL LOSE ALL YOUR DATA.
<yocum points over to the drbd/failsafe mailing lists> ;-)
> > > Which is exactly the reason to avoid the above mentioned configuration.If
> > > one card dies you have just lost all your data.
> > Personally, I'd bet on a drive or two going out before the controller.
> >I haven't had any sort of drive controller (IDE/SCSI/RAID) go out in
> >nearly a decade, but I've had plenty of drives go South on me.
This is definitely a more likely senario. But, even in the event that we
lose 50% of our data, we're still 100% screwed, so I might as well have the
space/speed that I want/need. If I was really paranoid, I'd be putting my
data on some fibre channel array or using drbd or something. I'm more
interested in tons of space really, really cheap.
> I have seen lots of drives go bad too. But don't discount Murphy. You might
> just have a bad day and a firmware upgrade of your controller resets the
> raid set. Most people with more then one 3ware card will set it up in JBOD
> mode and then use it as a software raid5 with a external log.
> > > Which was exactly what happend. They raid
> > > controller (Ami megaraid) got upset after one disk died and they lost
> > therI
> > > complete Mysql Database.
> > Since this isn't the place, I won't point out the obvious flaws in
> >their backup/recovery scheme.
> What's a backup? And recovery is for wimps ;)
File system? Who needs a file system? I edit inodes by hand! ;-)
> I just feel that my data would not be safe with the setup that you have
> provided. They even had bugs in the 3ware raid config which caused
> corruption in degraded mode. If that happens on your raid0 array or any
> array you are going to lose data. But I think that the chances of severe
> damage will grow in this raid0 setup.
FWIW, I got really good at reliably corrupting my data with the 3ware 6800
card and RAID5: just turn off a drive while it was writing. Bad things
happened. I've been testing 3 7810 cards they lent to me a couple weeks
ago, and I haven't had a problem yet (after ~10TB write/reads and ~12
simulated drive failures under a variety of high and low I/O and CPU duty
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