[dm-devel] - info about dm

[Luca Berra]

Vega,
you should probably address dmraid related question to the ataraid
mailing list.
i am cc-ing the mentioned list, and doing a full quote for that reason


On Wed, Nov 07, 2007 at 02:51:52PM +0100, Vega Forneris wrote:
>Dear all,
>
>I just installed Scientific Linux 5 and I used for the first time DM
>drivers for working with the embedded RAID (the servers are IBM xSeries,
>with an Adaptec HostRAID ASR - SATA). I really appreciate the fact that
>now Linux is able to recognize such devices, but I had some troubles
>configuring it and I’d like to have some info for better understanding
>how things work. 
>
>I’ll be a little “verbose” for clarifying what I did and which are my
>doubts

>
>1) Installation & Configuration
>I installed SL5 on a system which was running SL3 with HW drivers
>released by IBM. Linux was able to identify correctly the device
>(installed through CD), mapped it as /dev/mapper/asr_ and proceeded with
>he installation.
>
>Anyway, I found a little problematic configuring it manually: I tried to
>install SL5 on a node which was misconfigured: instead of seeing one
>device, it was managing the 2 HD (/dev/sda and /dev/sdb) as 2 separate
>devices an if I tried to configure them (at install time, via CD or
>network boot) with  DM, I got many errors about the RAID table (“ERROR:
>asr: Invalid RAID config table checksum on /dev/sda” or even “asr:
>Invalid magic number in RAID table; saw 0x0 expected
”). I tried to
>reconfigure the RAID card first via BIOS and then trying again to
>configure it via Linux (“dmsetup create 
”) but even if it seemed
>working (exit code 0), then querying the device asr_ (i.e. “dmraid –r”)
>resulted in errors as reported above
or better, dmraid commands (-r,
>-ay, -tay,
) reported errors, while dmsetup commands  (status, ls,
)
>worked normally. The only way I found for well-configuring the device
>was to install SL3 with specific drivers, and then to install SL5 with
>DM
both commands now work perfectly
>
>In brief:
>
>If I try to configure DM-RAID from scratch and I get such errors, how
>can I do? What’s that “RAID table”? Where is it written? Not in the MBR
>of an HD, ‘cause I tried to copy the MBR of the cloned disk which had no
>problem (still recognized as “good” for RAID and DM) and nothing
>changed

>
>2) Managing disks
>I configured disks in RAID 1 (mirror) but I wonder how to manage this
>RAID; in particular, how can I do for:
> - stopping a device (disk) and put it offline/and viceversa? 
> - reconfiguring/rebuilding it (due to broken/faulting HD)? 
>
>At the moment I should change a couple of disks (SMARTD warnings
>reported), but I’m scared about the “RAID table error”

>
>Many Thanks in advance for all help you can give me

>
>Best Regards
>Vega Forneris
>
>+--------------------------------------+
> Vega Forneris
>
> CNR – Servizi Informatici di Campo
> Gestione servizi GRID
>
> Area di Ricerca Roma II - Tor Vergata
> Via del Fosso del Cavaliere, 100
> 00133 Roma
>
> Tel:   +39 06 4993 4667
> Fax:   +39 06 4993 4650
> Email: Vega.Forneris at sic.rm.cnr.it
>+--------------------------------------+
>
>
>
>--
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>dm-devel at redhat.com
>https://www.redhat.com/mailman/listinfo/dm-devel

-- 
Luca Berra -- bluca at comedia.it
        Communication Media & Services S.r.l.
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