Purchasing new hard drives (noob question)

[NOT_Bill_Gates]

I am graduating from a very simple FreeNAS 7 (re-purposed laptop) to a REAL server using an Intel server board and will create a RAIDZ2 array. I am now in the process of purchasing NAS-friendly hard drives and this question is probably stupid to some, but it's this: I know I will get drives of similar capacity and type, planning two for parity and 4 for data, BUT how does it work when one dies and it has to rebuild. Does it wait until I replace the drive and then rebuild, does it turn one of the parity drives into a data drive? Should I purchase drives now that should just simply sit and wait on a shelf to fill in when needed? I figure as time goes on, whatever drives I buy now will eventually be replaced by their manufacturer with newer technology and thus those same drives may no longer be available when I need them.

 

[hugovsky]

Hi and welcome. You seem to be planning your nas well. Be sure to read the cyberjoke's noob guide.

About your questions...

If you have more than 6 sata ports, you can plug a new drive and replace. If you only have 6 ports, you have to remove the faulted drive, attach a new one and replace :). If using RAIDZ2, as you stated, pool redundacy will be reduced while doing this. You can lose another drive while resilvering and don't lose your data. (with RAIDZ2, you can lose 2 drives without losing data)

You can use different vendor drives as long as size is the same.

 

[Robert Trevellyan]

You should probably start by reading this guide, as well as the various hardware recommendations. One key fact you should gather from it is that there are no dedicated parity drives in ZFS. Parity information is spread across the drives as needed.

Having read and understood the guide, you may still be asking yourself whether it's best to have a spare drive on the shelf vs obtaining a replacement when you need it. As always, it depends, but it's worth knowing that unlike some types of hardware RIAD setups, ZFS (the filesystem underneath FreeNAS) does not require all drives in a vdev to be identical, nor even the same size. The only significant disadvantage to using drives of different sizes is that ZFS will treat all drives as being the same size as the smallest one.

So, one way to answer the question for yourself is to decide how much redundancy you will have in your pool, and from there, how long you can live with a degraded pool while you wait for a replacement to arrive. With only 6 drives in your pool, and assuming you go with a RAIDZ2 vdev layout, getting a replacement within a few days should be easy enough and a tolerable risk level for most users (it's unlikely you would see 2 more drives fail, which is what would lead to total data loss).

 

[Robert Trevellyan]

And of course, you will be backing up your data elsewhere too ... because RAID is not backup.

 

[NOT_Bill_Gates]

Excellent (and quick) help. I plan to read more on it and I appreciate all information you have provided. So, I take it that if I had spare port, one drive could be set up as a hot spare without having to remove the faulty drive, but I suspect having it spinning would significantly reduce its usable MTBF. So, I don't think I would have it installed and running just in case. I also probably would not keep it on the shelf, collecting cobwebs and becoming technologically more & more obsolete. Just buy a new one when needed. I do plan to use the NAS as backup, but not as SOLE backup. I am installing a USB 3.0 controller (since my older Intel server board didn't come with it) and will back up to external drives. I do NOT plan to bog down my server with any memory hogging services like Plex. One more question, unrelated to the hard drive question, will connecting both Gb ethernet ports to the same router help with throughput or just waste a port?

 

[Robert Trevellyan]

You could install a hot spare, but it doesn't make sense to me to run a RAIDZ2 pool with a hot spare when you could run a RAIDZ3 pool instead. What I'm doing is what you suggest, which is waiting until I need a replacement. My plan is to buy a 4TB (or larger) drive when one of my 2TB drives fails, to begin the process of in-place capacity doubling. Or maybe by then we'll all be buying 4TB SSDs...

If your NAS is solely a backup destination for other systems, you don't necessarily have to back it up, especially if you have the same data backed up offsite too. However, if anything on your NAS is only on your NAS, you definitely need to back it up.

USB3.0 it isn't yet well supported in FreeBSD/FreeNAS, and USB doesn't pass on any SMART data to the OS, so you might consider eSATA for external backup instead. But USB external drives are much better than no backup.

Regarding connecting multiple Ethernet ports, this won't be beneficial unless you have a bunch of users (10 is a figure I see mentioned a lot).

Make sure you get all your scrubs, SMART tests and email alerts set up correctly and you'll be in good shape.

 

[NOT_Bill_Gates]

Thank you. This was helpful. I don't plan on having anything on the NAS that isn't somewhere. I will probably use the USB ports mostly for filling info onto the RAIDZ2 pool. I currently have them as backups. After getting all of the data on it, then just incremental backups directly from the various computers over the network. What I may at that point do with the USB drives is create system images of the various systems and then keep those offsite.

 

[Robert Trevellyan]

I will probably use the USB ports mostly for filling info onto the RAIDZ2 pool. I currently have them as backups.

That's a nice idea in theory, but not as convenient as you might expect in practice. FreeNAS officially supports importing volumes from a few different filesystems but it's an all-or-nothing operation, i.e. it dumps the entire contents of the external drive into the destination that you select. I assume it preserves folder structure (never actually tried it), but you don't get to reorganize during import. Of course, you can reorganize later if you like, but in some cases it might be easier to copy data over the network.

EDIT: reading back, I see you've been using FreeNAS 7, which I believe supported mounted volumes with foreign filesystems. That functionality no longer exists in FreeNAS 9.3.

 

[diedrichg]

I will probably use the USB ports mostly for filling info onto the RAIDZ2 pool.

Don't connect external drives to the server USB ports, you will want to transfer your data from an external computer via FTP, CIFS, NFS. FreeNAS does not have graceful mounting and unmounting of USB drives.

 

[Z300M]

Don't connect external drives to the server USB ports, you will want to transfer your data from an external computer via FTP, CIFS, NFS. FreeNAS does not have graceful mounting and unmounting of USB drives.

I've mounted and unmounted USB-connected (both USB 2.0 and USB 3.0 -- the latter by way of an add-in StarTech USB 3.0 adapter) drives, copying data to and from them in between, without any apparent problems -- from the CLI, of course.

 

[NOT_Bill_Gates]

Wow! That does surprise me. It seems like basic functionality has been removed from the newer version of FreeNAS. Mounting & unmounting USB drives? And I specifically bought a USB 3.0 card that said it supported Linux & FreeBSD. Again, wow!

 

[hugovsky]

Yeah. There's lots of diferences from freenas 7. As @diedrichg said, it's better to use the network to copy file to/ftom usb drives.

 

[NOT_Bill_Gates]

OK. Gotcha. Probably not the right place to put this post and I certainly don't want to make people mad or get kicked off the forum, but does anyone know anything about NAS4Free and USB? I just hate to have wasted money on a USB card and front USB ports if I cannot use it. Plus, I would think it would take a LOT longer over the network to do multiple terabytes of data plus slow the network down for everyone else during those hours. Any thoughts?

 

[Robert Trevellyan]

don't want to make people mad

I don't think anyone minds discussion of other platforms, although sometimes they belong in the off-topic section.

This forum tends to be very conservative as far as what hardware gets the nod of approval. If something has been known to cause issues more than once, you will see people recommend not using it. Preservation of data is the #1 priority. So, there's a pretty good chance your USB3.0 adapter will work fine, but USB3.o issues have been seen more than once (particularly during boot), and are mentioned very frequently in this forum, hence people urging you not to use it. My impression of the NAS4Free forums is that they are less conservative.

Copying your data over the network probably will take longer, but not necessarily a lot longer, and it's something you'll only be doing once.

 

[NOT_Bill_Gates]

True. And thanks again. I believe I will try FreeNAS. I am mildly concerned because my (older) Intel server hardware is maxed out at 8 GB RAM but since it is a family/home use and will not likely have much simultaneous demands on it nor have other processes running (no Plex or other media streaming, etc...), I hope it will be OK.

You guys & gals have been very helpful and I very much appreciate it. Will post (in another section) how my install & setup went. Thanks to all who have helped and directed me to helpful resources.

 

[Robert Trevellyan]

Intel server hardware is maxed out at 8 GB RAM

Hopefully that's 8GB of ECC RAM. It's going to be a bit limiting, but you should be fine running a moderately sized and utilized pool with no jails or plugins.

 

[NOT_Bill_Gates]

Check. ECC RAM. No jails. No plugins. Just a big (OK, moderate) friggin zpool.