I have two EX4’s that I use strictly as network attached storage. The second EX4 is used to mirror the first one and my original plan was to use the EX4’s Remote Server backup feature to copy the individual shares but that turned out to be a non-starter because of problems with the EX4’s Remote Server backup which is actually a front-end for rsync. I haven’t read any messages here from others having the same issue so I wanted to wait until the next firmware release came out to see if anything was fixed before I described what I am experiencing. Speaking of experience, I bought my EX4’s last November and since them I have experienced many of the problems I’ve read about here and some that I haven’t:
I am not an rsync user in any other environment so someone may have to set me straight if this is how rsync works but in an EX4 to EX4 copy I see only about 3-4 MBs average speed on a Remote Server backup. The EX’s are connected to the same gigabit switch. The source EX4 is a 16Tb RAID5 and the target is a 12Tb RAID0. Currently disk sleeping is turned off and although I never tested it, I got the impression that the EX4 might actually sleep the disks while Remote Server backups were running causing them to fail.
On large shares the backup frequently fails without explanation making it difficult to feel confident that things are in sync. Failed backups also lead to another problem that may also be normal to the way rsync works but I haven’t checked to find out. When the backup starts the complete directory structure of the files to be copied is created on the target as the first step before file copying begins. If you manually stop the copy or it fails or is otherwise interrupted the folder structure that was copied remains on the target but the EX4 user/group permissions are set to root/root for those folders which have not been fully copied which makes it impossible for the user to delete or copy over them from their workstation. Depending upon your workstation settings these folders may also be hidden leading to further confusion as to why you can’t copy your (same named) files to the share. To remove them you must use ssh or delete and re-create the share. Folders that have copied are set to the correct user/group.
I am currently syncing the two EX4s with third party software running on an old PC but it’s extra complexity and cost for something that should have worked out of the box. The upside is that the performance is much higher - on the order of 60MBs with the new firmware but I shouldn’t have had to take this step.
Has anyone else used this successfully between two EX4s?