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14h
comment SSH tunneling is faster than OpenVPN, could it be?
(1) OpenVPN should use the largest MTU available on your network path. Probably 1500 bytes (maybe not). (2) openVPN interface needs to have MTU based on this. calculate by subtracting the openVPN overhead from original MTU. (3) kernel's TCP software ("stack") needs to know about this MTU, and set the TCP MSS based on this value. If you are lucky, this all happens automatically. But there are many MTU options in the docs so it probably doesn't, not always. To test, check your tcpdump. Are all the packets in a bulk xfer the same size? Or are they alternating long and short?
16h
comment SSH tunneling is faster than OpenVPN, could it be?
This is even more interesting because openssh (which I presume you're using) has some well-known performance problems. Maybe the systems you're using have it patched already, I'm told some linux distros do that. See psc.edu/index.php/hpn-ssh/640 . Also, your "fragment 1300" means that every TCP packet is getting fragmented at 1300 bytes. To optimize throughput, I would want to (1) only have openvpn fragment when absolutely necessary, which is probably more like 1450 (2) see if i could get the tcp stack to set its MTU appropriately, which would be this same value.
1d
reviewed No Action Needed Share /home between datacenters
2d
revised What version of RHEL am I using?
add bit about running as a single command.
2d
suggested approved edit on What version of RHEL am I using?
2d
revised FTP/FTPS/SFTP/SCP - Speed comparison
copy edit, warning about WinSCP
Dec
16
revised ZFS - Is RAIDZ-1 really that bad?
minor copy edit
Dec
12
comment ZFS - Is RAIDZ-1 really that bad?
I use ZFS on Linux and Centos 6. I don't allow automatic updates of the kernel or of ZFS. I've had issues with ZFS/SCL borking, but I have never had data loss. For the record, btw, FreeBSD has a similar set of solaris compatibility routines, but they and ZFS are fully integrated into the distribution, which makes it a lot simpler to make things all work together. If I only wanted ZFS and file service, I'd probably run FreeBSD. In fact, that's what I used to do, but I use the box for other random stuff, which made ZoL more appealing.
Dec
12
comment ZFS - Is RAIDZ-1 really that bad?
I have a raidz1 running on 7 consumer drives of various ages. I have it scrub every 2 weeks. It often finds an error and corrects it. I recently lost a drive and lost a file which had a latent error. Luckily, it was a media file that I can easily replace. For my important data I still, of course, have backups.
Dec
8
revised Different speed on Internet connection by switching NICs. Can someone make sense of this?
typo
Dec
8
answered ZFS - Is RAIDZ-1 really that bad?
Dec
5
comment What are the the potential drawbacks of using non-OEM hard drives in a server?
Side note: the Dell H3x0 RAID controllers have poor performance. You almost certainly want H7x0.
Dec
5
answered What are the the potential drawbacks of using non-OEM hard drives in a server?
Dec
5
comment What are the the potential drawbacks of using non-OEM hard drives in a server?
I've always found the "validation/custom firmware" argument hard to swallow, for low end commodity servers like the poster has. The corollary to that is that, for instance, LSI doesn't test its controllers with seagate OEM enterprise hard drives.
Dec
5
comment What are the the potential drawbacks of using non-OEM hard drives in a server?
I know that in at least some cases IBM also uses LSI controllers.
Dec
2
answered How can one efficiently use S3 to back up files incrementally?
Nov
26
awarded  Scholar
Nov
26
accepted Linux (non-transparent) per-process hugepage accounting
Nov
17
comment POST of MTU + ~798 bytes gets lost
One relatively simple test is to replace your modem. Firmware bug in that could do something like this. Without any visibility into the network beyond that, there's not much you can do.
Nov
14
awarded  Self-Learner