Replication - rotating drives

[Maverick]

Hi

I have a freenas unit at home and I replicate it to an old desktop as a backup. I want to take the drive out of the old desktop off site and this would be changed every 3 months or so.

When I plug in the offsite drive back in, will it just sync up? or will it do it from scratch?

My snapshots are only 2 weeks as the oldest.

Thanks in advance

 

[Robert Trevellyan]

When I plug in the offsite drive back in, will it just sync up?

This sounds like something you'd have to manage by hand. You should detach the pool before you remove the drive. At that point if you had an automatic replication task set up, it would have no destination pool.

 

[Maverick]

Correct. I would Disable the replication from and then detach the pool to remove it physically and take it to the beach house that is 3 hours away.

Just wondering if it would work when I plug the drive back in months later to update.

I only really want to turn on this other pc on when I want to let it replicate to take off site

 

[Robert Trevellyan]

Just wondering if it would work when I plug the drive back in months later to update.

In that case, I don't see why not.

I only really want to turn on this other pc on when I want to let it replicate to take off site

You might consider using an eSATA port and a drive dock.

 

[Maverick]

I wanted to do that but I'm out of sata ports. All 6 are used for the main z2

 

[Robert Trevellyan]

If you have a PCIe x1 slot free you can install an add-in card. I'm only suggesting this as something a bit more convenient than a whole 2nd PC, if that's all you're using it for.

 

[Maverick]

Good thinking. Don't know why that hadn't crossed my mind

 

[Michael M]

Largely spurred by the discussion above, I just bought an eSATA drive dock for a similar plan of alternating two hard drives for backup with at least one kept off site. So far, so good. Despite the advice otherwise on the forums, I had given USB a try. USB 3.0 is far too buggy and unreliable. USB 2.0 is slow, and while it works better than USB 3.0 on FreeNAS, other posts indicate that reliability and bugginess are problems with all USB external drives in NAS systems needing good reliability. In the end, I collected enough data to convince myself of the common forum theme that USB is a bad option in FreeNAS.

Just wondering if it would work when I plug the drive back in months later to update.

My understanding and experience so far are that it depends on which snapshots exist on the main pool/filesystem and which ones exist on the backup. If there is at least one snapshot common to both, it is possible to perform an incremental replication using the -i or -I flags for zfs send. If there is no common snapshot, full replication is the only option. (I would be happy to be corrected on this point because it would speed and simplify my process.)

To deal with this advantage of keeping older snapshots for infrequent replication, I made a scheme similar to http://docs.oracle.com/cd/E19120-01/open.solaris/817-2271/gbcxl/ and scheduled a periodic snapshot task that takes a snapshot every 4 weeks and keeps the snapshot for 2 years in addition to some snapshot tasks with higher frequencies and shorter lifetimes. I plan to adjust the frequencies and lifetimes depending on how much the space it takes ultimately seems wasteful for my purposes.

 

[Maverick]

I managed to get a m1015 controller yesterday, so I'm going to use this. I did plug it in briefly yesterday and it had an alert about the firmware on it, so I'll need to flash it. I looked at esata docks, but I'm skeptical of the chipsets that they use and would rather have something on the HCL for freenas. I've got an external psu for an internal hard dive and i'll just run a long sata cable out the back of one of the pci slots in the case to sit on top of the case when I need to plug in an external drive.

Now to debate if I put my 6 drives onto the m1015 or continue with the onboard x9scl, as they are all 4tb red drives, i wouldn't suspect much difference in performance.

For my snapshots, I setup cyberjocks guide of hourly/2d, daily/1m, 4wks/1year. Having the yearly snaps will always allow the disk to just sync up and not have to start from scratch.

 

[Michael M]

For what it's worth, my eSATA dock is connected to a Dell PERC H200 flashed with LSI9211-8i HBA firmware like the M1015. It works well so far. SATA & eSATA differ in cabling and connectors. It appears that the dock does pass through for eSATA mode although I cannot state so for certain. The cabling from SFF-8087 to SATA to eSATA adds potentially weak links to the chain, but I am comfortable with it for my home user level use.

Please let us know how well your system works.