ratio of storage : cache : parity & best allocation for my available drives


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I'm about 5 days into my unraid journey and am super stoked about the whole system.  I'm progressively moving data (mostly plex media, retro gaming resources and roms, and local home user files) off of my current desktop "server" to external USB 3 drives.  I'm adding drives and zeroing them in preparation for a big dedicated unraid server migration.

 

I will be mostly serving files, running radarr / lidarr / sonarr + nzbget, plex, general file serving, time machine for 2 hackintoshes, and run a few VMs to learn on.  I have 3x8gb of ram with 3 slots open if that makes a difference.  Local home use with occasional remote plex streaming.

 

Question 1

Is there a proper ratio of storage : cache : parity?

 

Question 2

Does my planned (penciled in) drive allocation make sense

 

SATA III Drives I plan have dedicated to unraid:

Platter drives

  • 8TB WD
  • 5TB Seagate
  • 5TB Seagate
  • 5TB WD
  • 2TB Hitachi
  • 1TB Hitachi

SSD Drives

  • 120 GB PNY
  • 60 GB OCZ

 

Other drives that could go in the mix

  • 250 GB SSD
    • could be added for additional cache
  • 8TB WB USB 3
    • I was thinking about using for occasional backup of important files brough to friend's house.  I have google accounts for most important documents and photos but nothing formalized 

 

I was thinking about the following:

Parity - 10 TB

  • 8TB WD
  • 2TB Hitachi

Cache - 180GB or 430 GB

  • 120 GB PNY
  • 60 GB OCZ
  • 250 GB (do I need this here really?)

storage drives - 16 GB (for now)

  • 5TB Seagate
  • 5TB Seagate
  • 5TB WD
  • 1TB Hitachi

Occasional backup of "important" files - not plex media

  • 8TB WB USB 3.0
    • I have one open SATA port on my mobo, should I just shuck this and put this in the array and use google or other cloud backup for document and photo backup?

Thanks in advance!

 

 

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5 minutes ago, sharpfork said:

Parity - 10 TB

  • 8TB WD
  • 2TB Hitachi

You can have dual parity, but they don't add together. Each must be at least as large as the largest single data disk in the array. Unless you buy another 8TB you will just use single parity of 8TB.

7 minutes ago, sharpfork said:

Occasional backup of "important" files - not plex media

  • 8TB WB USB 3.0
    • I have one open SATA port on my mobo, should I just shuck this and put this in the array and use google or other cloud backup for document and photo backup?

You could shuck the USB disk as you say and use it for parity2. But backups are very important. Parity is no substitute. You must have another copy of anything important and irreplaceable. You could just use this as a USB drive using the Unassigned Devices plugin.

17 minutes ago, sharpfork said:

Cache - 180GB or 430 GB

  • 120 GB PNY
  • 60 GB OCZ
  • 250 GB (do I need this here really?)

There are several ways to configure cache. The best way in my opinion is to just use the default raid1, that way you get redundancy. It is simpler if you have 2 SSDs the same size for this, but you could also use those 3 SSDs as raid1 if you have ports to spare. You would only get 180G capacity that way though since it has to mirror.

 

How much cache capacity you need depends on your specific uses. SSD Cache is usually used as working storage for your apps and VMs so they will get better performance and won't keep parity and other drives spinning. How much capacity you also want to have for "caching" writes to user shares is up to you.

 

One other thing. It is probably best to do the initial data load without caching, since cache won't have enough capacity to take it all and will just get in the way. You can also do the initial load without parity to get faster writes, as long as you have backups.

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Thanks trurl!

 

I have much more reading to do for sure!

 

I've been reading up on the "unlimited" GDrive space for 5+ users for $10/month.  I might just let them manage my remote backup needs and use Rclone or nextcloud (lots of reading there too) to backup.  I likely don't need more than a couple of gigs of backup anyway and don't need versioning so I need to rethink if it makes sense to have the 8tb as backup, if I should use a smaller drive, or if I should use gdrive (or some combo).

 

If I do shuck the other 8TB, you suggest going with RAID1/ mirror on the 2x 8TB as Parity?  Would I do this using the raid ability of my mobo or via software (I'm a noob). 

Nothing in my setup would be super time sensitive as far as needing a quick recovery.  Kids could watch netflix and other streaming services if plex is dead for a week. 

38 minutes ago, trurl said:

The best way in my opinion is to just use the default raid1, that way you get redundancy. It is simpler if you have 2 SSDs the same size for this, but you could also use those 3 SSDs as raid1 if you have ports to spare. You would only get 180G capacity that way though since it has to mirror.

I'll have to read up on this more.  I now see that having added the 120 GB + 60 GB, my cache shows up in unraid as 90 GB.  What advantage does this have over just having the single 120 GB and more space?  These drives aren't likely to be used for other stuff in the house as they can't hold much of an OS but the 250 could end up in a little linux box as a boot drive.

38 minutes ago, trurl said:

One other thing. It is probably best to do the initial data load without caching, since cache won't have enough capacity to take it all and will just get in the way. You can also do the initial load without parity to get faster writes, as long as you have backups.

I'll have to read up on this too

 

Thanks again!

Edited by sharpfork
fixed trurl's handle
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1 minute ago, sharpfork said:

Thanks Constructor!

Your welcome "Newbie" (is that your name? 😉)

 

2 minutes ago, sharpfork said:

RAID1/ mirror on the 2x 8TB as Parity

That isn't the way it works either. Parity and Parity2 are independent and use different methods of calculating parity.

 

4 minutes ago, sharpfork said:

having added the 120 GB + 60 GB, my cache shows up in unraid as 90 GB.

This is actually displayed incorrectly. You really only get the capacity of the smaller since it is a mirror, so just 60GB. There is a whole section of the FAQ dedicated to cache pools for further reading:

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?page=2&tab=comments#comment-554741

 

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