Hi,
From previous messages in the list I had the notion that partition size
was only limited by the operating system capabilities.
In fact this is not always a correct assumption. Playing around with our
brand new disk array, we have created a 4 Tb partition on a (Debian)
Linux box with XFS, created volumes in it with openAFS 1.4.1 and even
mounted them on client machines. So far, so good.
But when we try to write something to a volume we get a "no space left
on device" message.
Using the "fs diskfree" command returns:
Volume Name kbytes used avail %used
test.volume2 97975296 731912516-633937220 747%<< <<WARNING
The "vos partinfo" command returns:
Free space on partition /vicepa: -633937220 K blocks out of total 97975296
We checked and rechecked, deleted, recreated, salvaged... no joy.
A 2 Tb partition worked without a glitch.
Eventually we went back to the sources in tar.gz form, run "configure"
and poke around the code. In src/vol/partition.h, we found that struct:
struct DiskPartition {
struct DiskPartition *next;
char *name; /* Mounted partition name */
char *devName; /* Device mounted on */
Device device; /* device number */
int lock_fd; /* File descriptor of this partition
if locked; otherwise -1;
* Not used by the file server */
int free; /* Total number of blocks (1K) presumed
* available on this partition
(accounting
* for the minfree parameter for the
* partition). This is adjusted
* approximately by the sizes of files
* and directories read/written, and
* periodically the superblock is read
and
* this is recomputed. This number can
* be negative, if the partition starts
* out too full */
int totalUsable; /* Total number of blocks available on
this
* partition, taking into account the
minfree
* parameter for the partition (see the
* 4.2bsd command tunefs, but note
that the
* bug mentioned there--that the
superblock
* is not reread--does not apply here.
The
* superblock is re-read periodically
by
* VSetPartitionDiskUsage().) */
int minFree; /* Number blocks to be kept free, as
last read
* from the superblock */
int flags;
int f_files; /* total number of files in this
partition */
};
As you can notice various data (free, totalUsable...) are coded as ints
so we suspect that, on 32 bits platforms, the corresponding capacity is
stuck to 2 Tb (2 Giga x 1 kb blocks).
We did not look any further into the code but the same kind of
definition is probably found in many different place. We did not have
the time/capacity to fix throughout such a huge piece of code as the 60+
Mb of openAFS. After all, is it worth it since we are not advocating for
such big partitions as 4 Tb: waiting for a fsck of such a beast will
take whole coffee crop of Costa Rica (or maybe that of Brazil). But if
you, as we are, are foolish enough to play this game, be warned: it does
not work, at least on Linux x86.
Best regards,
Serge Torres
LIP
Ecole normale superieure de Lyon
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