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Jan
17
comment Automatically delete files by writing zeros on Linux
I did a bit more research. Am I right in thinking that by punching zeros I can shrink a TP logical disk down to the actual space used on the guest, whereas with TRIM the logical disk will only grow when there are no free blocks available (because with TRIM the logical disk knows which blocks are free on the guest) ?
Jan
16
accepted Automatically delete files by writing zeros on Linux
Jan
16
comment Automatically delete files by writing zeros on Linux
Sorry @ewwhite, I asked my question before clicking on the fstrim link. It says right at the top that the filesystem can be mounted!
Jan
16
comment Automatically delete files by writing zeros on Linux
Yup, I imagine such a utility would have to hook very deep into the OS, if not the kernel itself. We use zerofree to punch the zeros, but the disk has to be unmounted...
Jan
16
comment Automatically delete files by writing zeros on Linux
Thanks. Didn't know about fstrim, we use zerofree. Can fstrim work on mounted file systems? Zerofree requires they be unmounted, which greatly complicates automation via scripting.
Jan
16
asked Automatically delete files by writing zeros on Linux
May
15
answered Network packets flowing both ways but still can't communicate
May
15
accepted Rackspace - if I delete a server will I lose the backups?
May
15
awarded  Supporter
May
15
revised Packets returning but traceroute fails
edited body
May
15
comment Packets returning but traceroute fails
ABSOLUTELY AMAZING - IT WORKS!! I've been bashing my head on this problem all week and just today spent 12 hours on it. God bless you @kaspered you are brilliant!
May
15
accepted Packets returning but traceroute fails
May
15
comment Packets returning but traceroute fails
BTW, traffic from eth1's own subnet can get through OK.
May
15
awarded  Commentator
May
15
comment Packets returning but traceroute fails
Same thing happens. Wireshark sees the probes coming in but they are not replied to. It is as if all incoming traffic on eth1 is dropped even though the firewall is disabled and iptables is empty.
May
15
comment Packets returning but traceroute fails
Nope - exactly the same issue. Wireshark sees the echo replies but they don't make it back to the ping command.
May
15
comment Packets returning but traceroute fails
That's a fantastic answer! I tried setting rp_filter to 0 for eth1 but nothing changed. I don't think I've got an asymmetric routing problem because all the hosts on all the subnets have the same L3 switch as their default gateway. In fact, the topology for eth0 is identical to eth1. At the moment the default route is via eth0, but if I change it to eth1 then all the above works but the problem just moves to eth0. I'm convinced it has something to do with eth1 not being the 'default' NIC. BTW, /proc/sys/net/ipv4/ip_forward is intentionally zero.
May
15
revised Packets returning but traceroute fails
added 19 characters in body
May
15
asked Packets returning but traceroute fails
May
15
comment Network packets flowing both ways but still can't communicate
@DennisNolte After disabling eth0, the traceroute command gave the same results. This is not a surprise because even with eth0 enabled the first hop is the switch interface at 192.168.12.1 which is correct for eth1.