[KLUG Members] backing up

[Dirk H Bartley]

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Bruce Smith wrote:
> 
> > I am having a little trouble backing up.  I am using tar as follows:
> > tar -cvzpf /dev/st0 -T /root/backup/whattobackup
> >
> > when I restore the files with :
> > tar -xvzpf /dev/st0 it restores and then hangs.  When I try backup and then
> > restore a small amount of data it completely hangs and fails on the restore.
> > (control c stops the hang.)
> 
> What kernel version are you running?  I noticed some strange behavior with
> tar and some of the later kernels that I haven't had time to investigate.
[root@srv1 bin]# uname -a
Linux srv1 2.2.19-7.0.1 #1 Tue Apr 10 01:56:16 EDT 2001 i686 unknown

> 
> Any messages in /var/log/messages or dmesg about I/O errors, etc.???

No log messages at all.

> 
> Did it ever work?  Did it suddenly stop working?  If so, what changed?
> (new kernel, ....?)

I tried about a month ago to test the tape drive.  I did succeed at a basic
backup and restore, but it did hang at the end of the restore then and I did not
think much about it.  Now it is still doing it and when I backup just a few kb
and then restore it, nothing but hang time.

> 
> Otherwise you may need to "strace" tar to figure this out.

See attached. I don't know what to make of it other than it is stopping on a
read, of what I can't tell.

> 
> > I also noticed from man tar that you can put a hostname before a tar.   -f,
> > --file [HOSTNAME:]F  What mechanism does this use and does it work/is it secure
> > like with ssh.
> 
> It is NOT secure and should only be used on machines behind a good firewall.
> I think it requires an entry in the remote machine's /root/.rhosts file for access.
>
 
Insecure, very bad.  I am behind a firewall though, hummmmmm.

Dirk
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[root@srvbai1 /root]# strace tar -xvzf /dev/nst0 
execve("/bin/tar", ["tar", "-xvzf", "/dev/nst0"], [/* 30 vars */]) = 0
uname({sys="Linux", node="srvbai1", ...}) = 0
brk(0)                                  = 0x806d1b0
open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat64(3, 0xbfffeb8c)                  = -1 ENOSYS (Function not implemented)
fstat(3, {st_mode=S_IFREG|0644, st_size=26371, ...}) = 0
old_mmap(NULL, 26371, PROT_READ, MAP_PRIVATE, 3, 0) = 0x40018000
close(3)                                = 0
open("/lib/librt.so.1", O_RDONLY)       = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240\"\0"..., 1024) = 1024
fstat(3, {st_mode=S_IFREG|0755, st_size=153956, ...}) = 0
old_mmap(NULL, 71860, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x4001f000
mprotect(0x40025000, 47284, PROT_NONE)  = 0
old_mmap(0x40025000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x5000) = 0x40025000
old_mmap(0x40027000, 39092, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x40027000
close(3)                                = 0
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`\300\1"..., 1024) = 1024
fstat(3, {st_mode=S_IFREG|0755, st_size=5155229, ...}) = 0
old_mmap(NULL, 1214792, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x40031000
mprotect(0x40151000, 35144, PROT_NONE)  = 0
old_mmap(0x40151000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x11f000) = 0x40151000
old_mmap(0x40156000, 14664, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x40156000
close(3)                                = 0
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`\300\1"..., 1024) = 1024
fstat(3, {st_mode=S_IFREG|0755, st_size=5155229, ...}) = 0
close(3)                                = 0
open("/lib/libpthread.so.0", O_RDONLY)  = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`O\0\000"..., 1024) = 1024
fstat(3, {st_mode=S_IFREG|0755, st_size=509469, ...}) = 0
old_mmap(NULL, 89144, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x4015a000
mprotect(0x40168000, 31800, PROT_NONE)  = 0
old_mmap(0x40168000, 32768, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0xd000) = 0x40168000
close(3)                                = 0
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`\300\1"..., 1024) = 1024
fstat(3, {st_mode=S_IFREG|0755, st_size=5155229, ...}) = 0
close(3)                                = 0
munmap(0x40018000, 26371)               = 0
getpid()                                = 27323
getpid()                                = 27323
rt_sigaction(SIGRT_0, {0x40163a50, [], 0x4000000}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {0x40162e20, [], 0x4000000}, NULL, 8) = 0
rt_sigaction(SIGRT_2, {0x40163ae0, [], 0x4000000}, NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [RT_0], NULL, 8) = 0
_sysctl({{CTL_KERN, KERN_VERSION}, 2, 0xbffff64c, 31, (nil), 0}) = 0
time(NULL)                              = 1000135129
brk(0)                                  = 0x806d1b0
brk(0x806d1e0)                          = 0x806d1e0
brk(0x806e000)                          = 0x806e000
rt_sigaction(SIGCHLD, {SIG_DFL}, {SIG_DFL}, 8) = 0
geteuid32()                             = -1 ENOSYS (Function not implemented)
geteuid()                               = 0
umask(0)                                = 022
brk(0x8071000)                          = 0x8071000
pipe([3, 4])                            = 0
fork()                                  = 27324
close(4)                                = 0
fstat64(3, 0x806cc00)                   = -1 ENOSYS (Function not implemented)
fstat(3, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
read(3,

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