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bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?
From: |
Linda Walsh |
Subject: |
bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine? |
Date: |
Thu, 11 Oct 2012 23:39:16 -0700 |
User-agent: |
Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.8.1.24) Gecko/20100228 Lightning/0.9 Thunderbird/2.0.0.24 Mnenhy/0.7.6.666 |
Paul Eggert wrote:
On 10/11/2012 08:11 PM, Linda Walsh wrote:
I find that if I try to use a read size of > (2G-8K), I get partial read errors.
My guess is that it's your kernel, or maybe your
file system, and not dd per se. Try running 'strace'.
open("/dev/Home+Space/Home", O_RDONLY|O_DIRECT) = 3
dup2(3, 0) = 0
close(3) = 0
lseek(0, 0, SEEK_CUR) = 0
open("/dev/null", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3
dup2(3, 1) = 1
close(3) = 0
mmap(NULL, 2147495936, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
-1, 0) = 0x7f1e5efae000
read(0,
"XFSB\0\0\20\0\0\0\0\0\20\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
2147483648) = 2147479552
read(0,
"XFSB\0\0\20\0\0\0\0\0\20\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
2147483648) = 2147479552
write(1,
"XFSB\0\0\20\0\0\0\0\0\20\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
2147479552) = 2147479552
read(0, " this.context.sourceBoxHighlig"..., 2147483648) = 2147479552
open("/usr/share/locale-langpack/en_US.UTF-8/LC_MESSAGES/coreutils.mo",
O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY)
= -1 ENOENT (No such file or directory)
----
Maybe has something to do with lvm...am guessing...I was trying to dd
read from an lvm device raw....
I'll look into it...but I'm not even getting error messages if I try to
do 4G @ a time...
dd if=/dev/Home+Space/Home bs=2G count=4 of=/dev/null iflag=direct
dd: warning: partial read (2147479552 bytes); suggest iflag=fullblock
0+4 records in
0+4 records out
8589918208 bytes (8.6 GB) copied, 9.1148 s, 942 MB/s
dd if=/dev/Home+Space/Home bs=4G count=2 of=/dev/null iflag=direct
dd: warning: partial read (2147479552 bytes); suggest iflag=fullblock
0+2 records in
0+2 records out
4294959104 bytes (4.3 GB) copied, 5.4533 s, 788 MB/s
dd if=/dev/Home+Space/Home bs=8G count=1 of=/dev/null iflag=direct
0+1 records in
0+1 records out
2147479552 bytes (2.1 GB) copied, 3.58152 s, 600 MB/s
...
The larger the block size asked for... the smaller I got???
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Linda Walsh, 2012/10/11
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Paul Eggert, 2012/10/12
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?,
Linda Walsh <=
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Paul Eggert, 2012/10/12
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Pádraig Brady, 2012/10/12
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Paul Eggert, 2012/10/12
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Pádraig Brady, 2012/10/12
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Linda Walsh, 2012/10/12
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Linda Walsh, 2012/10/12
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Eric Blake, 2012/10/12
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Linda Walsh, 2012/10/12
- bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Eric Blake, 2012/10/12
bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?, Linda Walsh, 2012/10/12