Re: 32-bit vs AMD64 on Opteron for LAMP server
Douglas Allan Tutty wrote:
Without the driver, will the card just look like a non-raid card or will
the drives not be visiable at all? If the drives are visible, forget
the hardware raid.
Without the driver (either dpt_i2o or i2o_block) the hard drives are not
visible at all, and you cannot boot. You need the driver to see the
drives. As others have pointed out, this doesn't mean the RAID card
isn't "real" hardware RAID; as with any other piece of hardware on the
system, the kernel requires a driver to interact with it. The driver is
not binary; I have the source code patch from Adaptec, which you need to
build into the kernel for AMD64. It is not included with Etch because
the "community" apparently made a decision that two different drivers
for the same hardware were not needed, and they decided that they would
go with i2o_block. I have heard that i2o_block has some issues with
stability, people have talked about corruption and errors under load.
Since the i2o_block driver has apparently been abandoned for a while, I
don't have a great deal of confidence that these problems were ever
really fixed. The dpt_i2o driver has worked very well for me for about
two years now, with no problems at all under load, so I would prefer to
continue using that. I recently communicated with Mark Salyzyn over at
Adaptec, and he forwarded me the current source code version of dpt_i2o
which works with the current 2.6 kernels. I haven't had the chance to
try it out yet.
Even if I go with jbod, I would still need one of these drivers just to
see the hard drives. I have no handle on whether the hardware RAID would
be better or worse than software RAID.
Fairly early in the install, there's a menu item "continue install from
ssh". Is there no way to get remote access to the console so that the
datacenter people only have to put CD-bin1 into the drive?
I have never seen this option (I recently installed Etch from scratch on
my home workstation, after my hard drive died). How is this accessed?
Where do you get the (no doubt arcane) information that is needed to
access the option, since it plainly wasn't visible during the stock install?
You can do software raid right from the installer. My box has two
drives, with LVM over raid1 for the system including swap. Grub can
boot off of raid1 so put /boot on raid1 (no LVM) partition.
Again, I saw no option for software RAID. I did see an option for LVM
during the partitioning section, but nothing at all about RAID. How
would I enable that?
That's almost 2 years ago. You may find that "it just works". If you
No, it won't - I know for a fact, from the guy at Adaptec himself, that
dpt_i2o is not included with AMD64 because the maintainers decided that
they would be going with i2o_block. So I may be able to install using
i2o_block, but that isn't the path I want to take since I have no
confidence in that module for a production environment, and doing
searches on google for it I can find no references to it except from the
2005 timeframe. This does not give me confidence that it was developed
or fixed past the time when people were reporting that it had problems.
So best case, I can maybe install using i2o_block, and then build my own
kernel that uses dpt_i2o. However I need to be at the console to do
this, because inevitably there will be hangs and suchlike that require
my physical presence at the console.
could find someone else with this card, even if they don't usually run
debian, they could boot the installer CD and go through the motions and
see if the drives appear as one drive (hardware RAID working) or many
(no hardware RAID).
Unfortunately, the RAID card I have doesn't seem to have been a type
that really took off in any significant way. I don't know of anyone else
who has one. If anyone does happen to have a spare Adaptec Smart RAID
2015S lying around in an unused server, then I'd love to hear whether
they can try installing Etch and patching the kernel with the new
dpt_i2o. But somehow I think anyone with such a server is probably using it.
Thanks,
/Neil
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