Also Sprach Marc W. Mengel:
> In 2.4.3 (currently in beta) you can stripe a backup accross two tapes
> with the RAIT code, but to do so you have to throw the parity stripe away,
> so if either tape fails, you lose both.
>
> Otherwise you can just run two amdumps, and have each one do roughly
> half of your data.
>
> -----
> Marc Mengel <[EMAIL PROTECTED]>
>
I've downloaded Amanda 2.4.3b3 and compiled it with only minor incident.
In client-src/sendbackup-dump.c, line 218:
217: "xfsdump",
218: no_record ? "-J" : skip_argument,
219: "-F",
This file will fail to compile with
'no_record' undeclared (first use in this function)
The compile took place on a Mandrake Linux 8.1 system with the 2.4.8 kernel
with XFS patches. Changing the line to
options->no_record ? "-J" : skip_argument,
solved the problem.
I set up two Ecrix VXATape drives and the null device as
rait:/dev/nst{0,1,2} with the drives at 0,1 and nst2 linked to /dev/null.
I then did an amflush of some level 0 dumped filesystems on my holding
disk.
The flush fails with
START amflush date 20020416
START driver date 20020416
STATS driver startup time 0.030
ERROR taper no-tape [rewinding tape: Success]
FINISH driver date 20020416 time 30.147
and amflush mails a report stating that nothing was flushed.
So out of curiosity I removed the nst2/null device from the
rait: list. I started the amflush again. lsof indicated
3 tapers writing to /dev/{nst0,nst1}, and /dev/null even
though /dev/null was not explicitly specified.
This time the amflush succeeded and wrote the capacity of one
VXATape, around 28GB but not the expected 50-60GB. Checking on the tapes
with amrestore, I discovered that the data written to /dev/nst1
was the exact mirror of what was written to /dev/nst0! So the
RAIT driver, though it doesn't say so in the docs, supports mirroring
of tapes in a two drive configuration. Is this intentional?
If so, how does one specify the rait: line so it uses /dev/null
to throw away parity and get a striped rather than mirrored
backup?
Also, how does one recover from a RAIT set? Can amrestore be used
or does one have to use amdd?
If both striping with parity, w/o parity, and mirroring are
to be supported, perhaps rait0:, rait1:, and rait3: rather than
rait: would be clearer in amanda.conf.
--
C. Chan < [EMAIL PROTECTED] >
PGP Public Key: finger [EMAIL PROTECTED]
