New Disc Configuration


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I currently have an Unraid server set up as a test with 3 VMs which I have now got configured to my liking.

 

I want to replace the drives in there with much larger ones, can I simply put new drives in place of the old ones, then choose new configuration, then connect each drive as an unassigned device to copy the existing data from?

 

Thanks

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Just now, Spies said:

Currently have no parity running, but I guess I could add one of the 3TB drives as parity and go from there?

Yep. Your signature clearly says 1TB parity and 4x1TB data, so that's what I assumed you were running. Since you haven't kept your signature current, maybe it would be good to detail exactly what you have right now and what you intend to end up keeping. My advice may change depending on circumstances.

 

Do all your drives, current and pending, have clean bills of health? SMART data good, fully tested, etc?

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Sorry my signature is misleading as that's my current machine at home, I've just put another one together for work.

 

I need to get some sata to sas cables before I can check the pending drives but nothing is mission critical yet, as I haven't moved the data from our server onto it, I just have the 3 VM's running which have replaced physical machines.

 

Current config was thrown together so I could play with the VMs, 4x500gb 1x128gb ssd cache

Edited by Spies
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15 minutes ago, Spies said:

Current config was thrown together so I could play with the VMs, 4x500gb 1x128gb ssd cache

 

1 hour ago, Spies said:

I want to replace the drives in there with much larger ones

 

25 minutes ago, Spies said:

one of the 3TB drives as parity

Parsing all this together, I assume you have 5x3TB drives that you want to end up in the array? It would be so much easier if you would just tell us what you have instead of making us tease it out of you line by line.

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1 hour ago, Spies said:

I currently have an Unraid server set up as a test with 3 VMs which I have now got configured to my liking.

 

I want to replace the drives in there with much larger ones, can I simply put new drives in place of the old ones, then choose new configuration, then connect each drive as an unassigned device to copy the existing data from?

 

Thanks

 

I don't know what your business application is, but if it is write intensive then adding parity is going to slow things down considerably. If the data is being backed up (like any business server would be), I might suggest passing on the parity and just running it unprotected. Historically, unRAID's big value add is the parity protection, but the user shares, packaging / integration with Docker and VM technology make it a viable platform for those not needing parity, so long as backup is handled.

 

Your approach outlined above would work just fine in this scenario.

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Sorry for not giving the full story with regards to the hardware inside, i was trying to post quickly between jobs.

 

The intention is to have 3x 3tb plus parity (so slightly different configuration to now). But now reading that the write performance will be crippled I'm wondering how to go about backing up the data. I would assume that VM performance would also be crippled if it was to reside on a parity protected array? Do people generally have a single unprotected drive for their vdisks and copy them onto a removal medium to back them up?

 

Can parity writes be improved with additional hardware?

 

For the sake of full disclosure, the business is just an IT shop but we image customers machines over a gigabit network, so writes to that share need to be fast, the other uses are a file store (700GB) for program installers which rarely change.

 

Can you parity protect independent shares or is it all or nothing?

 

The server does have hardware RAID5 also, would that play nice with unRaid if you run it in unprotected mode?

Edited by Spies
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Typically people load things that need fast access on an SSD, which is often mounted as the "cache" disk. The cache disk can be used to buffer writes to the array, and then later (in the middle of the next), the files are copied to the array, and although it might be a bit slow, you are sleeping and don't care. But the disk is also used to store VM and Docker files for fast access. If the cache disk isn't big enough to store your files, they are written to the array and you loose the speed advantage. SSDs are pretty big these days, but not sure how big your image files are gong to be.

 

You can use a non-SSD as cache, and that drive will be faster than your network speed. Or have an SSD disk as cache, and another disk mounted outside the array that is used in your re-imaging if there is no need to have it protected.

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18 hours ago, Spies said:

But now reading that the write performance will be crippled I'm wondering how to go about backing up the data.

Can parity writes be improved with additional hardware?

Just turn on Turbo Write, I get nearly line speed (112MB/s) writes the the parity protected array with Turbo Write enabled.

http://lime-technology.com/wiki/index.php/Tips_and_Tweaks#Turn_on_Reconstruct_Write

This has the side effect of spinning up all hard drives during the write, but for large image files it is absolutely worth it.  An SSD is still the preferred location for VMs and Dockers, though.

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As always, your mileage will vary.  I've heard people getting in the 60MB/s range with Turbo Write.  I never get much below 70MB/s, but I'm writing primarily to fast 6TB drives.  That said, the first thing I do when I touch a machine coming to me for support is image it to an external HD, then copy the image from the HD to the array.  That's really the sweet spot for turbo write, I commonly get nearly full Gb line speeds.

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