Back Up of Network Storage System

A couple of years ago I had a ‘funny’ case with Network Attached Storage (NAS) by Cisco/Linksys (NSS 4000 and NSS 6000). The idea was to create a backup solution for a company where all important documents from desktops and laptops would be backed-up. Dropbox started about a year earlier and it was not a solution for this particular company (cloud and enterprise data). There was a product called Continous Data Protection (CDP) by Tivoli/IBM, which worked pretty much like OwnCloud or DropBox but within the internal network.

The solution was simple. We set up two NAS and install everybody CDP. All data goes first to the one of NASs and then this NAS is backed up on another NAS. Once a week the drives in the second NAS were about to be changed and the cycle was meant to be repeated a couple of times as we have bought 24 drives and there were 4 bays in each NAS. It is worth mentioning that when we have ordered hard drives they were on the list of recommended drives by the NAS’s manufacturer. When we tried to set up any kind of RAID array it simply could not succeed. After contacting Linksys/Cisco they informed us that the drives were not on the list of supported drives. Fortunately the seller was kind enough to replace them with another (supported model).

But there was a slight problem. The backup feature of the NAS did not work. It was hanging up the whole device. Either it was backup on external device (in this case it was another NAS, I also tried server) or even the same NAS but different drive, it did not work. It took me a couple of weeks emailing the support back and forth before they acknowledged that there was an issue with a device.

  1. First I showed that the device internal backup option does not work regardless of NAS I used (we had two different versions NSS 4000 and NSS 6000). We got a replacement for one of them, it still did not work.
  2. Second thing I showed was that it did not matter whether the destination drive was internal or external.
  3. Then I proved that if the backup source is big enough (in GB) the process will fail.
  4. Finally I showed that the problem was with the number of files, not ths size (in GB) of the source. I simply created loads of copies of 1 byte files, that caused the backup to fail.

Unfortunately, they did not fix it in the next firmware but somewhere later on.

So the only option we had at that time was a bit risky. We created a RAID 1+0 array and instead of backing up we were taking out the mirrored pair of disks out and recreating the array with a new pair of disks.

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