RN42800 new install with 8 HGST NAS 8TB Drives how to set up as X-Raid with Raid 5

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johnw248 wrote:

 

I was using the Netgear Raid Calculator which shows 8x8 in X-Raid as 43.6 and Flex-Raid Level 5 at 50.8 which to me is losing an additional drive or that the "extra" protection costs the same as one 8TB HGST NAS drive.

 

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There are two different units used for disk space.  Manufacturers use TB (1000*1000*1000*1000 bytes), most operating systems use TiB (1024*1024*1024*1024 bytes). Unfortunately most software (including ReadyNAS) mislabel the TiB (calling it TB).  This mislabeling didn't matter much in the ancient times when 2 GB was a large disk.  But the difference today (with 8-12 TB drives) is considerable.

8x8 RAID-5 gives you 56 TB (ignoring a bit of overhead), which is the same as ~50.9 TiB.  8x8 RAID-6 gives you 48 TB, which is the same as ~43.7 TiB.  The Netgear RAID calculator does account for the overhead I generally ignore, so it's numbers are a slightly smaller.

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johnw248 wrote:

 

...which to me is losing an additional drive or that the "extra" protection costs the same as one 8TB HGST NAS drive.

 

That's just too costly for my purposes, these are media files and while I wouldn't want to lose them, the extra protection for two disk failures is too high.

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That is your call of course. 

Either way you should consider your future storage needs.  Horizontal expansion (filling empty slots) is considerably cheaper per TB gained than vertical expansion (replacing working disks with larger ones).  So filling all the slots when you purchase is usually not the best long-term strategy.

For example, 8 TB HGST disks cost about $250 (US amazon pricing), while the 10 TB version costs about $350.  12 TB are about $430.

6x10TB would cost $2100 up front and give you 50 TB of RAID-5 storage.  8x8TB costs $2000, and gives you 56 TB of storage.  That's $100 less up front, and of course more space up front.

But if you need to expand your NAS to 60 TB later, then the total costs change.  Expanding 6x10TB to 60 TB costs you $350 for one more 10 TB disk -  60 TB for $2450 total.  And you'd still have one more slot to expand again - giving you 70 TB for $2800. 

Expanding 8x8TB to 60 TB would require replacing two 8 TB drives with 12 TB models - $860 at current prices  or 60 TB for $2860 total.  And going to 68 TB after that would require you to spend another $860 (replacing two more 8 TB drives with 12 TB models) - 68 TB for $3720.

So if your media library is growing, then you should consider starting with 10 TB or possibly even 12 TB disks, and leave some empty slots for future expansion.