Valerie Aurora Henson wrote: > On Wed, Apr 08, 2009 at 05:45:47PM -0400, Nick Dokos wrote: >> but there is an interesting catch-22: how do I save its output? >> >> I can try the command line suggested in the manual page: >> >> e2image -r <dev> - | bzip2 > image.bz2 >> >> but it takes forever: I started a run on Saturday and it was not >> done by Tuesday when I killed it - writing to the pipe at 4096 bytes >> a pop is very slow. >> >> Or I can forego the compression and try to save to a file: it's sparse >> (I only used 7GiB before it failed), but its nominal size exceeded the >> maximum file size limit on ext4, at which point I start getting lseek >> failures. We really need some e2image format which encodes the sparseness, I think... > The 16TB limit on ext4 files is an enormous pain for testing 64-bit > (>= 16TB) file systems. I keep intending to write some simple dm > setup to concatenate two loopback files together, but instead I always > install XFS and create a loopback file on an XFS partition. For testing a large device, say /dev/sdb1 is 10GB large: # TERABYTES=`expr 20 \* 1024 \* 1024 \* 1024 \* 2` # 20 TB in sectors # echo "0 $ERABYTES zero" | dmsetup create zero1 # echo "0 $TERABYTES snapshot /dev/mapper/zero1 /dev/sdb1 p 128" | \ dmsetup create sparse1 This will create a 20TB sparse device called /dev/mapper/sparse1 that has 10GB of actual storage space available. If more than 10GB of data is written to this device, it will start returning I/O errors. This is from Documentation/device-mapper/zero.txt -Eric -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
