Desired content: NAS box failures

[mikeh2]

NAS boxes provide RAID Level1 to protect from hard disk failures, but the boxes themselves are a new point of failure. I'd like to see this topic addressed.

If the box is running RAID1 can the disks be removed, attached to any Linux based machine for file recovery? I would guess so.

If running RAID0 then if either the box or either hard disk fails, you're screwed. True?

Perhaps the most interesting issue is if the box is taking two small internal hard disks and presenting them to the outside world as one large hard disk. In that case, can the data on the disks be recovered if they are removed from a failed NAS box?

 

[thiggins]

Thanks for the suggestion. I already took one run at this in Smart SOHOs Don't Do RAID. It points out the problem of relying on any single device, regardless of RAID level. Even with RAID, you need files backed up on another device, preferably in a different physical location for real data security,.

We also have added information on drive format to the NAS Chart Features page for each product. If NAS drives use standard file formats such as XFS, EXT3, etc, then drives can be mounted on another system for data recovery, regardless of whether RAID 0 or 1 is used.

 

[mikeh2]

Thanks, Tim, for the reply. Still, when two or more physical disks are presented to the outside world as a single disk image, the NAS box has to be doing some internal fudging. Even if the disks use a standard file system, I wonder if this fudging, whatever it is, would prevent data recovery if the disks were removed from the box. Perhaps a small point. I'll be able to test this soon as I finally bought my first NAS box. And on that score, your site is great. Thanks again.
Michael

 

[Dennis Wood]

The only way to deal with a NAS failure is to have a spare on hand. With Rsync being pretty much standard on the boxes, you could make a business case for purchasing two units and using one of them as an offsite rsync host. This setup allows scheduled hands-off offsite backups and in the case of the QNAP boxes, an email notification of any backup failures. In the case of a failure, the offsite box would become the onsite box until the failed NAS could be repaired.

It's also a very good idea to purchase an extra hard drive spare when you poplulate your NAS. This way when one drive fails, you'll have an identical replacement on hand, again in the interest of not having a compromised NAS unit while waiting for an RMA replacement.

Very few of the businesses I've visited over the years have any kind of disaster plan in place which is pretty risky considering that hardware failures are pretty much guaranteed over a period of time. There is peace of mind in working through a complete workstation to server disaster plan, testing it, and then monitoring the various backup strategies to ensure they're working. The current crop of NAS units make this type of planning very easy.

 

[claykin]

Tim

Recovery via PC may be an option, but Readynas users beware!!!

Beginning with V4.x firmware the Duo/NV+ and 1100 units will format using 16KB block size. This CANNOT be read on any typical PC hardware. Its apparently a hardware limitation and requires a Sun Sparc or Itanium workstation to read discs formatted in 16KB blocks.

Thanks Netgear!

Read here for more details:

http://www.readynas.com/forum/viewtopic.php?f=10&t=21003

http://readynas.com/forum/viewtopic.php?f=18&t=21030&start=0&hilit=4KB+block

Thanks for the suggestion. I already took one run at this in Smart SOHOs Don't Do RAID. It points out the problem of relying on any single device, regardless of RAID level. Even with RAID, you need files backed up on another device, preferably in a different physical location for real data security,.

We also have added information on drive format to the NAS Chart Features page for each product. If NAS drives use standard file formats such as XFS, EXT3, etc, then drives can be mounted on another system for data recovery, regardless of whether RAID 0 or 1 is used.

 

[thiggins]

Thanks, claykin. I was aware of that and the info is posted in the Features page of those (and other ReadyNAS products) that share the limitation.

The good news is that the Intel-based ReadyNAS Pro doesn't have the problem
and uses standard EXT3.

 

[claykin]

Yup, and if Netgear responds to the outcry, they'll offer a 4KB formatting option in a future firmware release for the affected products.

I suspect with the introduction of the Pioneer series (Pro series lesser sibling), Netgear will obsolete the NV+ and possibly the 1100. The will leave the Duo as the only product still using the somewhat outdated Infrant CPU.

Thanks, claykin. I was aware of that and the info is posted in the Features page of those (and other ReadyNAS products) that share the limitation.

The good news is that the Intel-based ReadyNAS Pro doesn't have the problem
and uses standard EXT3.

 

[mikeh2]

Thanks. Using the Qnap box with automated rsync backup does indeed seem like a great approach.

 

[Monkey]

I love a good offsite Rsync as much as the next man, however if Johnny SoHoUser user deletes or overwrites the file, does Rsync protect you as well as a proper backup & media rotation schedule?

 

[corndog]

Well, you could run rsync without the delete option. That way your synchronized copy will still have the files that got removed on the original.

The downside to this is that your offsite backup will gradually grow significantly larger than your original. It takes half a second for a user to move a folder containing 500G of data. But then your offsite would have two copies of that 500G

So it's not a perfect solution.

 

[briandorling]

If you are worried about the backup size increasing continually then Dirvish is a possible solution.

Dirvish is a perl script wrapper based on rsync so uses rsync to do the real work. But you can configure dirvish (for example) to keep multiple copies of files (I have always between 15 and 90 days worth of backups in Dirvish). The secret is that it uses hard-links, which means a file may only be physically present once. But for each backup day I have what looks like a complete directory tree of what I backed up (which is a directory tree off the client), so no fancy tools required to get the data off the backup again, just a simple copy will do. Due to the hard-link useage space consuption is very reasonable, but means your NAS must use an FS that supports hard-links.

The machine being backuped up must support rsync, there is for example a version for XP, so windows clients are supported OK.

Cheers Brian