Compiling rsync with -Os

I have been trying to figure out why rsync was Segfault-ing when trying to transfer several hundred gigabytes from the old server to the new one.

It was working fine but I interrupted it a few times. And then, when I was down to 5-6 gigabytes it would transfer a file or two (small files at that) and just spit out a weird message, like 
rsync error: errors with program diagnostics
or it would complain about a timeout (I am copying from an NFS volume, what timeout?), or simply receive a Segfault.

In a desperate attempt to figure out at least when the problem was occurring I decided to rebuild it with debugging symbols enabled. 
env CFLAGS=-ggdb3 emerge -av rsync
I then fired up gdb an ran the problematic commands 
gdb
run -avPAH /remote/... /var/....
and it worked fine. Since I had -Os in my CFLAGS, I tried using -O2 instead and still, there were no problems.

Lesson learned, -Os does break stuff.

Update: Well, -O2 saved the day for a while but rsync again started segfaulting when I tried to copy a directory with 16000 files (well, 8000 files each with an extra hard link). So I compiled it with no optimization, or better said, with no specific optimization and it worked. For how long I wonder.

Update: I was obviously chasing ghosts. Here is a follow up.

Comments

Post a Comment

Popular posts from this blog

FreeIPA cluster with containers

Notes on how to install a FreeIPA cluster on Ubuntu. Mostly following the instructions on https://github.com/freeipa/freeipa-container Start with what would be the primary host. If you install a third replica you would want to review the replica agreements to ensure you have a two-way replication between all pairs of nodes.
Read more

ADSL Router Model CT-5367 user and pass (VIVACOM)

Writing down the username and password for the vivacom ADSL router, in case I need it again. user: root pass: warmWLspot Useful to telnet 192.168.1.1 and then reboot . Originally found at Neo2SHYAlien blog . And here I found passwords for other models, just in case. ZTE ZXDSL 832 username: root password: GSrootaccess ZTE ZXDSL 831 username: root password: GSrootaccess ZTE username: root password: 831access Huawei SmartAX MT882 username: root password: MT882rootaccess ZTE ZXDSL-531b username: root password: rootWLaccess Pirelli – DRG – A124G username: root password: warmWLspot Comtrend CT-5367 username: root password: warmWLspot HG530 Home Gateway username: root password: warmWLspot
Read more

Installing Gentoo with full disk encryption

The purpose of this exercise - install Gentoo where all disk partitions are encrypted. Boot from a system rescue disk and partition the disk - use GPT partition table where the first partition is reserved, second is the boot, and the third one is for the rest of the data. Device Start End Sectors Size Type /dev/sda1 2048 32767 30720 15M BIOS boot /dev/sda2 32768 442367 409600 200M Linux filesystem /dev/sda3 442368 375093902 374651535 178.7G Linux filesystem Encrypt partitions number 2 and 3, and open them cryptsetup luksFormat /dev/sda2 cryptsetup luksFormat /dev/sda3 cryptsetup luksOpen /dev/sda2 crypt_boot cryptsetup luksOpen /dev/sda3 crypt_data Format the boot partition mkfs.btrfs /dev/mapper/crypt_boot Prepare LVM for the rest, and format the top level vgcreate vg0 /dev/mapper/crypt_data lvcreate -l 100%FREE -n data vg0 mkfs.btrfs /dev/vg0/data Mount and set up any subvolumes mount /dev/vg0/data /mnt/gentoo btrfs subvol create /mnt/gentoo/@ /mnt/gentoo/@home umount /mnt/gentoo Now...
Read more