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Is an Auto-tiered Disk library supported?

  • 4 January 2022
  • 2 replies
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Hi,

Is it possible to use an auto-tiered (SSD to NLSas disks) storage as a disk library?

Does Commvault support an auto-tiered disk library? What happens if the backed up data moved from a fast tier to slow tier?

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Best answer by Laurent 4 January 2022, 15:05

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Hi @huseyin 

It is possible to use an auto-tiered library and different vendors have different implementations for how tiering operations are performed.

You will need to consider read and write performance when selecting a library as write performance may well be fast, but depending on the tiering implementation, read operations could suffer from significantly lower performance.

For example, when reading data, how is the data retrieved from slower tier? What size is the fast or cache tier?

When deduplication is also considered, potentially a read operation may require many smaller segments referenced across multiple files. If whole files are need to be recalled from slow tier to fast tier before being read, then performance costs to read a small amount of data can be quite high if whole files are needed to be moved through the tiers to read a small segment of those files.

Thanks,

Stuart

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Hi,

Is it possible to use an auto-tiered (SSD to NLSas disks) storage as a disk library?

Does Commvault support an auto-tiered disk library?

 

Hi @huseyin !

 

Yes, it’s technically possible as long as the MediaAgent can access it.

You can even use spindle USB disks (but it’s not recommended, of course).

 

 

What happens if the backed up data moved from a fast tier to slow tier?

 

Then, as explained by @Stuart Painter , it depends on the device, but, what I would have answered straight is ‘it will be slow’ if you need to access that data.

 

When you paid (much) for Commvault software, you can consider you paid for the intelligence that’s build into this product, and would prefer not invest some more money into some storage device’s intelligence (but maybe more into faster storage).

Auto-tiering devices may be best for primary storage of living data (I mean, not backup data), or with other backup software that do not provide deduplication.

 

And if you still consider to use such device for backup, whatever backup software is used, just picture the situation when you would need to perform a massive restore (like you’ve been cryptolocked and need to restore your whole latest backup of anything you manage). If your device is big enough to store all those ‘latest backups’ inside its SSD tier, you’re partly saved. If not, you know you’ll have to wait for long.

 

It’s all only my humble opinion, of course. 

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