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ReadyNAS RN42400 OS 6.8 to ReadyNAS RN42400 6.8 Mirror
I purchased a second ReadyNAS 42400 w/ "indentical" 2T drives and want to "mirror" the second NAS to the primary. I see Netgear has at least two ways to back up a NAS but it's not clear which is the...
It was a while ago that I posted that, I don't recall who the respondent was at this point (or if he is still active).
I don't believe he was saying that the air bearing wouldn't fail, I think he was just saying that he didn't believe frequent spinups would cause them to fail faster than drives that were spinning 24/7.
Causes I've seen reported include electrical component failure, physical contamination, mechanical arm failures, and motor failures.
I know for certain that enabling spin down (and putting NAS on power schedules) saves power, and I don't have any clear data that says whether it increases failure risk or decreases it. In the absense of that data, I enable spin down and use power schedules.
If you pull, the backup NAS will hold off on a scheduled shut down until all scheduled backup jobs are complete. If you push, the target does not know there is a backup taking place and will shut down anyway.
Sandshark wrote:
If you pull, the backup NAS will hold off on a scheduled shut down until all scheduled backup jobs are complete. If you push, the target does not know there is a backup taking place and will shut down anyway.
Yes. Also, the backup won't start until the NAS is fully booted and ready to receive it. So if the backup isn't on 24x7, the backups are more robust if you "pull".
On the other hand, if you do a "push" backup, the source NAS will make a snapshot of the share,and back up the snapshot. That ensures the backup is coherent (nothing changing while the backup is running). So if you run the backup NAS 24x7, it is a little better to do a push.
OK! Now I'm really confused. Please see the attached file. It shows the current power management for the "Push" NAS. Seems to me if I had the "Pull" NAS configured the same way either one could wake the other up with a scheduled resync with 'Wake On LAN' set ON. No?
Is the example at:
https://kb.netgear.com/29929/ReadyNAS-OS-6-Setting-up-a-backup-job-with-rsync-over-SSH
Representative of how to set up resync? Or is there another more specific to my purpose? (Hopefully :^)
Will running a NAS 24/7 shorten its lifetime? (Used to be start-stops were the worse thing for a drive but that was years ago. What's the current opinion?)
Thanks for your suport and patience. Ron
No, the ReadyNAS cannot send a WoL to another system. Turning on WoL only sets it up to receive one. I believe there is a suggestion in the Idea Exchange to add the ability to send a WoL. But you would still have an issue with the target system shutting down -- either not doing so (because none is scheduled) or doing so before the job was complete (if it's not complete when a scheduled shut-down occurs).
I have seen no definitive studies to compare running continuosly vs power cycling. Common wisdom is somewhat split on the issue, especially when you throw drive spin-down into the mix. The drive manufacturers still use run time (MTBF) as their primary indicator Turning the system off definately saves power, both to run the system and to cool it. Living in Florida where I run my A/C for the majority of the year and havng my NASes in a room that is not the best cooled in the house, I power cycle my backup systems and don't run them at the same time. It iads in my comfort as well as keeping the NAS temperatures down. Since they are also on the same UPS as the main systems, that also leaves more backup time for the main systems most of the time.
Thanks Sandshark! I'll give resyncing a try...
Ron
PS - Running the drives 24/7 should be good for the disk surfaces but tougher on the bearings in the spindle and head-arm assembly. The effects of heat on the lubricants and precision of the bearings, I believe, contribute most to MTBF. As you said the drive mfgs. spec MTBF, probably because of the emence use of RAID systems for enterprise servers that do run 24/7.
PPS - I live in the Boise area so year round room conditioning is a must and electricity is pretty cheap due to lots of hydro power, so enviroment shouldn't be a problem.
RonGalwey wrote:
https://kb.netgear.com/29929/ReadyNAS-OS-6-Setting-up-a-backup-job-with-rsync-over-SSH
Representative of how to set up resync? Or is there another more specific to my purpose? (Hopefully :^)
https://kb.netgear.com/29741/How-do-I-back-up-data-between-two-ReadyNAS-OS-6-systems-using-the-backup-manager is better. You don't need rsync over ssh if you are backing up to another NAS on your home network. Regular rsync will do fine.
RonGalwey wrote:
It shows the current power management for the "Push" NAS. Seems to me if I had the "Pull" NAS configured the same way either one could wake the other up with a scheduled resync with 'Wake On LAN' set ON. No?
As Sandshark replied, it doesn't work that way. The NAS is just using "vanilla" rsync - it doesn't realize the source/destination is another readynas.
RonGalwey wrote:
Representative of how to set up resync? Or is there another more specific to my purpose? (Hopefully :^)
Will running a NAS 24/7 shorten its lifetime? (Used to be start-stops were the worse thing for a drive but that was years ago. What's the current opinion?)
I've never seen a research study on this (and no one here has ever cited one), so it really is just opinion.
I haven't measured my NAS power use yet (that's a project for later this fall), but I am estimating that keeping an x86 NAS running 24x7 with disk spindown disabled would consume about 600 kwh of electricity per year. That's 5% of my total power usage. So my backup NAS are on a power schedule, and my main NAS has disk spindown enabled.
Thanks Stephen,
I'll check out the script and I was thinking of scheduling the backup so I could spin the drives down. Because energy is cheap now, there is no sense in wasting it and putting a strain on the mechanics.
I used to work for IBM in their disk drive division, when they had one, and we never published MTBF studies or methods. They were industrial secrets. When the disks were coated with epoxy the head disk interactions of start/stops would cause some of the epoxy to shed
particles and combine with the lubricants put on the disk surfaces to prevent stiction. That amalgam would get stuck on the leading edge of the head making for an unstable head/disk interface. The head would eventually crash. With the advent of thin film disks and better lubricants, if any, the MTBF shifted to the mechanical parts like bearings. Heat and wear became the “new” culprit. But you're right - it's still just an opinion...
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