server(W2K3) with 2Disk-RAID1-array does not start again after booting with Knoppix 5.0.1

Hello,

I booted with Knoppix 5.0.1 a server with a 2 DiskRAID1-array
(RAID-adapter:
Adaptec 29320ALP(AIC-7902A)(HostRAID™ RAID 0, 1, and 10).

All partitions were recognized as single disks. I did not wrote any
data to the NTFS formated disks/partitions. Nevertheless after
unmounting all disks und shutting down the machine, Windows2003
did not at all start again.

Since I didnot have the time to check what happend, I immediately
restored a backup image (Acronis TrueImage). After that everythin
was fine.

Such a problem did never happen to me before after booting a single
disk machine with NTFS formated disks. What happend? Did I forgot
to turn off swapping before booting into Knoppix?


Any feedback is apprechiated very much. Thank you!

John

John wrote:
>
> Hello,
>
> I booted with Knoppix 5.0.1 a server with a 2 DiskRAID1-array
> (RAID-adapter:
> Adaptec 29320ALP(AIC-7902A)(HostRAID™ RAID 0, 1, and 10).
>
> All partitions were recognized as single disks. I did not wrote any
> data to the NTFS formated disks/partitions. Nevertheless after
> unmounting all disks und shutting down the machine, Windows2003
> did not at all start again.

The 29320 card you have is not a true RAID card, but one of Adaptec's
HostRAID cards. Under Linux you can use it with the aic_79xx driver as
a standard SCSI adapter, or with the a320raid driver to use the HostRAID
features. Unfortunately, the a320raid driver is closed-source (at least
the last time I checked) and is not included in the generic Linux
kernel. Thus I doubt Knoppix could or would include it. So Knoppix
couldn't possibly have known about the RAID setup. (Even if it is
included with Knoppix, you'd have to manually load it. Knoppix couldn't
possibly distinguish between a 29320 without HostRAID and one with it
enabled.)

I would guess that in that situation something in the configuration
(either in a reserved area of the disk or in the card's non-volatile
memory) got flipped back to non-RAID mode. IOW, using the disks as
single volumes once caused the card to forget about its RAID setup.

I doubt there's any workaround for this, other than to be sure to use
the a320raid driver instead of aic_79xx under Linux.

John-Paul Stewart schrieb:

> John wrote:
> >
> > Hello,
> >
> > I booted with Knoppix 5.0.1 a server with a 2 DiskRAID1-array
> > (RAID-adapter:
> > Adaptec 29320ALP(AIC-7902A)(HostRAID™ RAID 0, 1, and 10).
> >
> > All partitions were recognized as single disks. I did not wrote any
> > data to the NTFS formated disks/partitions. Nevertheless after
> > unmounting all disks und shutting down the machine, Windows2003
> > did not at all start again.
>
> The 29320 card you have is not a true RAID card, but one of Adaptec's
> HostRAID cards. Under Linux you can use it with the aic_79xx driver as
> a standard SCSI adapter, or with the a320raid driver to use the HostRAID
> features. Unfortunately, the a320raid driver is closed-source (at least
> the last time I checked) and is not included in the generic Linux
> kernel. Thus I doubt Knoppix could or would include it. So Knoppix
> couldn't possibly have known about the RAID setup. (Even if it is
> included with Knoppix, you'd have to manually load it. Knoppix couldn't
> possibly distinguish between a 29320 without HostRAID and one with it
> enabled.)
>
> I would guess that in that situation something in the configuration
> (either in a reserved area of the disk or in the card's non-volatile
> memory) got flipped back to non-RAID mode. IOW, using the disks as
> single volumes once caused the card to forget about its RAID setup.
>
> I doubt there's any workaround for this, other than to be sure to use
> the a320raid driver instead of aic_79xx under Linux.


Thank's a lot John-Paul for the helpful information! Would you say
that OnBoard SCSI-RAID adapters are seldom a good idea?

Thank's! John

John wrote:
>
> Thank's a lot John-Paul for the helpful information! Would you say
> that OnBoard SCSI-RAID adapters are seldom a good idea?

Depends on the RAID adapter. The on-board 29320-based stuff, which
Adaptec calls HostRAID, is really just software RAID with a little help
from the driver and the BIOS.

I've never seen real hardware RAID truely on-board. The closest I've
seen are the "zero channel RAID" adapters (from both LSI Logic and
Adapctec) that "convert" on-board SCSI to on-board RAID. Those are much
better, IMHO.

Usually an easy way to tell is that if something doesn't handle RAID-5
(Adaptec's HostRAID doesn't) then it's not true hardware RAID. (Note
that the converse is not necessarily true: handling RAID-5 is _not_
always an indicator of true hardware RAID.)

John-Paul Stewart schrieb:

> John wrote:
> >
> > Thank's a lot John-Paul for the helpful information! Would you say
> > that OnBoard SCSI-RAID adapters are seldom a good idea?
>
> Depends on the RAID adapter. The on-board 29320-based stuff, which
> Adaptec calls HostRAID, is really just software RAID with a little help
> from the driver and the BIOS.
>
> I've never seen real hardware RAID truely on-board. The closest I've
> seen are the "zero channel RAID" adapters (from both LSI Logic and
> Adapctec) that "convert" on-board SCSI to on-board RAID. Those are much
> better, IMHO.
>
> Usually an easy way to tell is that if something doesn't handle RAID-5
> (Adaptec's HostRAID doesn't) then it's not true hardware RAID. (Note
> that the converse is not necessarily true: handling RAID-5 is _not_
> always an indicator of true hardware RAID.)


Thank's again John-Paul for your tips! Does that also mean most U1
rackservers do only have onboad RAID controllers because there is
only space for 2 disks and therefore including a RAID5 adapter would
not make sense?

What are additional advantages of real hardware RAID-controllers if
used in U1 rackservers under Knoppix or Debian?

John

John-Paul Stewart schrieb:

> John wrote:
> >
> > Thank's a lot John-Paul for the helpful information! Would you say
> > that OnBoard SCSI-RAID adapters are seldom a good idea?
>
> Depends on the RAID adapter. The on-board 29320-based stuff, which
> Adaptec calls HostRAID, is really just software RAID with a little help
> from the driver and the BIOS.
>
> I've never seen real hardware RAID truely on-board. The closest I've
> seen are the "zero channel RAID" adapters (from both LSI Logic and
> Adapctec) that "convert" on-board SCSI to on-board RAID. Those are much
> better, IMHO.
>
> Usually an easy way to tell is that if something doesn't handle RAID-5
> (Adaptec's HostRAID doesn't) then it's not true hardware RAID. (Note
> that the converse is not necessarily true: handling RAID-5 is _not_
> always an indicator of true hardware RAID.)


Thank's again John-Paul for your tips! Does that also mean most U1
rackservers do only have onboad RAID controllers because there is
only space for 2 disks and therefore including a RAID5 adapter would
not make sense?

What are additional advantages of real hardware RAID-controllers if
used in U1 rackservers under Knoppix or Debian?

John

John wrote:
>
> Thank's again John-Paul for your tips! Does that also mean most U1
> rackservers do only have onboad RAID controllers because there is
> only space for 2 disks and therefore including a RAID5 adapter would
> not make sense?

I'm not quite sure what you're getting at with the above statement, but
on-board RAID adapters make plenty of sense with 1U servers, IMHO. I
have some Dell 1U servers with on-board RAID-5 capability. You can
configure a 3-drive RAID-5 array with the 3 internal drives plus there's
a second SCSI channel routed to an external connector (to use, say, one
of Dell's PowerVault external JBOD storage enclosures as a 14-disk RAID
array if you like). Having on-board RAID makes plenty of sense (to save
a PCI slot) in a 1U server, especially if it offers an external connector.

> What are additional advantages of real hardware RAID-controllers if
> used in U1 rackservers under Knoppix or Debian?

Real hardware RAID is easier to boot from (since the RAID is transparent
to the OS and bootloader). Real hardware RAID is either seen as RAID or
not seen at all---avoiding the problem with the cheap "Fake RAID"
controllers that started this thread (i.e., accidentally having RAID
component disks seen as individual disks instead of as a whole array
because of confusing driver support). Real hardware RAID-5 (in
particular) offloads overhead (of parity calculations) from the host CPU
to a dedicated RAID processor (which can be especially important on a
busy application server, or not at all important on a file server where
the CPU is largely idle).

There's a whole lot of tradeoffs between hardware RAID and software RAID
that are the same regardless of whether you're talking about 1U rack
servers or larger hardware, and regardless of whether you're talking
about Knoppix or Debian or any other distribution (or even any other
operating system, for the most part).

Plenty has been written about these trade-offs. If you want to know
more, Google can tell you a lot more than I can.

John-Paul Stewart schrieb:

> John wrote:
> >
> > Thank's again John-Paul for your tips! Does that also mean most U1
> > rackservers do only have onboad RAID controllers because there is
> > only space for 2 disks and therefore including a RAID5 adapter would
> > not make sense?
>
> I'm not quite sure what you're getting at with the above statement, but
> on-board RAID adapters make plenty of sense with 1U servers, IMHO. I
> have some Dell 1U servers with on-board RAID-5 capability. You can
> configure a 3-drive RAID-5 array with the 3 internal drives plus there's
> a second SCSI channel routed to an external connector (to use, say, one
> of Dell's PowerVault external JBOD storage enclosures as a 14-disk RAID
> array if you like). Having on-board RAID makes plenty of sense (to save
> a PCI slot) in a 1U server, especially if it offers an external connector.
>
> > What are additional advantages of real hardware RAID-controllers if
> > used in U1 rackservers under Knoppix or Debian?
>
> Real hardware RAID is easier to boot from (since the RAID is transparent
> to the OS and bootloader). Real hardware RAID is either seen as RAID or
> not seen at all---avoiding the problem with the cheap "Fake RAID"
> controllers that started this thread (i.e., accidentally having RAID
> component disks seen as individual disks instead of as a whole array
> because of confusing driver support). Real hardware RAID-5 (in
> particular) offloads overhead (of parity calculations) from the host CPU
> to a dedicated RAID processor (which can be especially important on a
> busy application server, or not at all important on a file server where
> the CPU is largely idle).
>
> There's a whole lot of tradeoffs between hardware RAID and software RAID
> that are the same regardless of whether you're talking about 1U rack
> servers or larger hardware, and regardless of whether you're talking
> about Knoppix or Debian or any other distribution (or even any other
> operating system, for the most part).
>
> Plenty has been written about these trade-offs. If you want to know
> more, Google can tell you a lot more than I can.


Hi John-Paul,
the following information helped me a lot:
> Real hardware RAID is easier to boot from (since the RAID is transparent
> to the OS and bootloader). Real hardware RAID is either seen as RAID or
> not seen at all---avoiding the problem with the cheap "Fake RAID"


Little change of topic..
Nowadays SAS(Serial Attached SCSI) becomes more popular and I am
wondoring if I should not go for such drives (for use in a mail
server)...


Thank's a lot for every feedback!

John

John wrote:
>
> Little change of topic..
> Nowadays SAS(Serial Attached SCSI) becomes more popular and I am
> wondoring if I should not go for such drives (for use in a mail
> server)...

Personally I have no preference between SAS and traditional SCSI devices
at the moment. Select a system based on your other criteria, and get
whatever type of drives the vendor offers in that system.