Attachment 81975 Details for Bug 117310 – file.diff

[patch] file.diff

file.diff (text/plain), 4.72 KB, created by tedm on 2007-10-18 21:10:01 UTC

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Creator: tedm

Created: 2007-10-18 21:10:01 UTC

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obsolete

>--- atacontrol.8.original	Thu Oct 18 10:57:18 2007
>+++ atacontrol.8	Thu Oct 18 12:37:44 2007
>@@ -221,6 +221,105 @@
> The new modes are set as soon as the
> .Nm
> command returns.
>+.Pp
>+The atacontrol command can also be used to create purely software
>+RAID arrays in systems that do NOT have a "real" hardware RAID card
>+such as a Highpoint or Promise card.  A common scenario is a 1U
>+server such as the HP DL320 G4 or G5.  These servers contain a SATA
>+controller that has 2 channels that can contain 2 disks per channel,
>+but the servers are wired to only place a single SATA drive on each
>+channel.  These servers do have a "pseudo" RAID BIOS but it uses
>+a proprietary format that is not compatible with the ata driver, and
>+thus their RAID bios must be switched off.  Another common scenario
>+would be a Promise UDMA100 
>+controller card that did not contain the Fasttrack RAID BIOS, but
>+did contain 2 UDMA channels. One channel would be put on 1 disk
>+and the other channel on the other disk.  It is NOT recommended to
>+create such arrays on a Primary/Secondary pair on a SINGLE channel
>+since the throughput of the mirror would be severley compromised,
>+the ability to rebuild the array in the event of a disk failure
>+would be greatly complicated, and if a disk controller electronics
>+failed it could wedge the channel and take both disks in the
>+mirror offline. (which would defeat the purpose of having a mirror
>+in the first place)
>+.Pp
>+A quick and dirty way to create such a mirrored array on a new
>+system is to boot off the FreeBSD install CD, do a minimal scratch
>+install, abort out of the post install questions, and at the command
>+line issue the command:
>+.Pp
>+.Dl "atacontrol create RAID1 ad4 ad6"
>+.Pp
>+then immediately issue a reboot and boot from the installation CD
>+again, and during the installation, you will now see "ar0" listed
>+as a disk to install on, and install on that instead of ad4, ad6, etc.
>+.Pp
>+To get information about the status of a RAID array in the system
>+use the command line:
>+.Pp
>+.Dl "atacontrol status ar0"
>+.Pp
>+A typical output showing good health on a RAID array might be as
>+follows:
>+.Pp
>+.Dl "ar0: ATA RAID1 subdisks: ad4 ad6 status: READY"
>+.Pp
>+If a disk drive in a RAID1 array dies the system will mark the disk
>+in a DOWN state and change the array status to DEGRADED.  This can
>+ALSO happen in rare instances due to a power fluctuation or other event
>+causing the system to not shutdown properly.  In that case the output
>+will look like the following:
>+.Pp
>+.Dl "ar0: ATA RAID1 subdisks: ad4 DOWN status: DEGRADED"
>+.Pp
>+For a mirrored RAID1 system the server WILL ALLOW you to remove a
>+dead SATA disk drive (if the drive is in a hot-swap tray) without
>+freezing up the system, so you can remove the disk and while your
>+obtaining a replacement the server can run off of the active disk.
>+The only caveat is that if the active disk is ad6, the system most
>+likely will NOT be able to be rebooted since most systems only
>+support booting off of the first disk drive.
>+.Pp
>+To deactivate the DOWN disk ad6 to allow for it to be ejected, use
>+the following:
>+.Pp
>+.Dl "atacontrol detach ata3"
>+.Pp
>+then eject or remove the disk. Note that this only works if the 2 disks
>+in the mirror are on separate channels (which is the standard setup for
>+1-U servers like the HP DL320)  When the new disk drive is obtained,
>+make sure it is blank, then shut the system down.  At this point, if
>+the system has a RAID array card like a Hipoint or Promise controller,
>+you may then boot it into BIOS of the card and use the manufacturers
>+RAID array rebuild utilities to rebuild the array.
>+.Pp
>+If the system has a pure software array and is not using a "real" ATA
>+RAID controller, then shut the system down, make sure that the disk
>+that was still working is moved to the bootable position (channel 0
>+or whatever the BIOS allows the system to boot from) and the blank disk
>+is placed in the secondary position, then boot the system into 
>+single-user mode and issue the command:
>+.Pp
>+.Dl "atacontrol addspare ar0 ad6"
>+.Dl "atacontrol rebuild ar0"
>+.Pp
>+If the disk drive did NOT fail and the RAID array became unmirrored due
>+to a software glitch or improper shutdown, then a slightly different
>+process must be followed.  Begin by issuing the detach command (this
>+shows the detach for disk ad6, the primary master on channel 3):
>+.Pp
>+.Dl "atacontrol detach ata3"
>+.Pp
>+then reboot the system into single-user mode.  (don't just init the system,
>+reboot it so that both disks get probed)  You will probably see TWO mirrored
>+RAID arrays appear during the boot messages, ar0 and ar1.  Issue the
>+command:
>+.Pp
>+.Dl "atacontrol delete ar1"
>+.Dl "atacontrol addspare ar0 ad6"
>+.Pp
>+Now a status command will show the array rebuilding.
>+.Pp
> .Sh SEE ALSO
> .Xr ata 4
> .Sh HISTORY

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