Anybody using DB2 9 on Linux x86, please, examine...

[Konstantin Andreev]

I'm almost sure I've found bad bug, but for a while I can't neither confirm nor reject this.

If anybody could make an independent test on it's own system, I'd appreciate it very much.

The possible bug is:

*************** *
*** DB2 refuses DEVICE containers bigger than 4Gb. ***
*************** *

DB2 version affected ( at least ):

| # db2level
| DB21085I Instance "dbi" uses "32" bits and DB2 code release "SQL09012" with level identifier "01030107".
| Informational tokens are "DB2 v9.1.0.2", "s070210", "MI00183", and Fix Pack "2".

The test is rather simple: just try in any database

| # db2 create tablespace X pagesize 4096 managed by database using ( device '/some/device' 1048576 )

The device must be bigger than 4G, and amount of pages indicated to DB2: any number >= 1048576 and <= (device size). The 1048576 because 1048576 * 4096 = 0x100000000, that is 4G.

If you get in response:
| SQL1422N The size of the container is invalid. SQLSTATE=54039

then you are affected too.
--
Konstantin Andreev.

[Jan M. Nelken]

Konstantin Andreev wrote:

I see 3 correct results, and 3 wrong results. But it's likely something
wrong in your code, not in ioctl(), because you mistakenly count BYTES
returned by ioctl(BLKGETSIZ E64) as SECTORS.

I can not review your code, because it's omitted, ...

Sorry about that - finger slipped. Here is the code:

------------------------------------------------------
/* Compile with "g++ -o GetDevSize -D_FILE_OFFSET_B ITS=64 GetDevSize.c" */

#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/statvfs.h>
#include <sys/param.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <errno.h>
#include <getopt.h>

#define BLKGETSIZE64 _IOR(0x12,114,s ize_t)
#define BLKGETSIZE _IO(0x12, 96)

int main (int argc, char *argv[])
{
int fh;
int rc;
size_t sectors = 0;
int pagesize = 4;
char *device = NULL;

if (argc < 2)
{
printf("\nSynta x: GetDevSize <device>\n\n" );
rc = -1;
return rc;
}

device = argv[1];

fh = open(device, O_RDONLY | O_DIRECT | O_LARGEFILE , 0600);
if ( -1 == fh )
{
printf("Error opening device \"%s\": %x\n", device, errno);
rc = 1;
return rc;
}
rc = ioctl(fh, BLKGETSIZE64, &sectors);
if ( 0 != rc )
{
printf("BLKGETS IZE64: Error calling ioctl: %x !\n", errno);
}
else
{
printf("BLKGETS IZE64: Device %s: rc=%u - %u sectors, %d %dK
pages\n",device , rc, sectors, sectors / (pagesize * 1024), pagesize );
}

close(fh);
return rc;
}
------------------------------------------------------

[Konstantin Andreev]

Jan M. Nelken wrote:

Sorry about that - finger slipped. Here is the code:

Here is your miss:

size_t sectors = 0;
rc = ioctl(fh, BLKGETSIZE64, &sectors);

LOL. You are getting the 64-bits value in the 32-bit variable. Certainly, you see only lowest bits.

Maybe IBM worth hire me for coding :) I can handle this :)...
--
Konstantin Andreev.

[Jan M. Nelken]

Konstantin Andreev wrote:

Here is your miss:

> size_t sectors = 0;
rc = ioctl(fh, BLKGETSIZE64, &sectors);

LOL. You are getting the 64-bits value in the 32-bit variable.
Certainly, you see only lowest bits.

Maybe IBM worth hire me for coding :) I can handle this :)...

Oh - now I get it:

There is an ioctl BLKGETSIZE that returns the size (in 512-byte sectors)
of a block device in 32 bits.
There is an ioctl BLKGETSIZE64 that returns the size (in bytes) of a
block device in 64 bits.

Not too consistent - I would say.

I am not related to hiring process at IBM at all - so cannot help you
here. But - you were too eager to blame DB2 - an IBM product.
Thanks anyway

Jan M. Nelken

[Konstantin Andreev]

Jan M. Nelken wrote:

Sorry about that - finger slipped. Here is the code:

Sorry, the error is more subtle.

Somebody mistakenly assumed that if BLKGETSIZE64 is formally defined as

#define BLKGETSIZE64 _IOR(0x12,114,s ize_t)

then ioctl() returns sizeof(size_t) value... But

1) the contrary is clearly documented:
--- ( from linux/fs.h )----
#define BLKGETSIZE64 _IOR(0x12,114,s ize_t) /* return device size in bytes (u64 *arg) */

2) it's easy to note, that 64-bit value can't fit in 32-bit 'size_t' (on 32-bit platform).

Hence, ioctl(BLKGETSIZ E64) has not an implementation error, but feature.
The situation is clear now, thank you for intresting discussion.
--
Konstantin Andreev.

[Konstantin Andreev]

Jan M. Nelken wrote:

But - you were too eager to blame DB2 - an IBM product.

:) I generally flay without regard for rank. IBM or DB2 is not special case.

--
Konstantin Andreev.

[Serge Rielau]

Konstantin Andreev wrote:

Jan M. Nelken wrote:

>But - you were too eager to blame DB2 - an IBM product.

:) I generally flay without regard for rank. IBM or DB2 is not special
case.

A man to my liking.

--
Serge Rielau
DB2 Solutions Development
IBM Toronto Lab