Red Hat Topics - Write block limit of 2GB on x86_64?

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Author Write block limit of 2GB on x86_64?
dorth

2005-04-25, 5:46 pm

Hi,
I'm having a problem with writing greater than 2GB of 512kb blocks to
either an ext3 FS or a reiser 3.6 FS (my specs are fedora core 3 64bit
on a 4way opteron with 2.4GHZ cpu's and 32GB of memory).

The Disk I am writing to is a SATA raid device with 1.6TB of capacity
(adaptect sata raid card).

If I perform the following:
dd if=/dev/zero of=testfile bs=2048M count=2

I get a testfile of size = 4294950912k as expected.

however, If I do:
dd if=/dev/zero of=testfile bs=4096M count=1

I get testfile = 2147475456k

So is this a bug or does this mean that although I can write files
greater than 2GB in size, I can't write them greater than 2GB 1KB
blocks a time?

My mount options are defaults.

thank you for your help.
dorth

2005-04-26, 5:46 pm

Well nevermind. I did some more googling and found:

"sys_sendfile limits itself dumbly to 2GB even on 64bit architectures"

I need to use a binary that has "sys_sendfile64" enabled.
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