Which size HDDs for new storage server build?

[xfataa]

Hello!


I'm currently using a software RAID consumer 4 bay NAS with 4 x 1.5 TB in RAID 5. Needless to say I ran out of space pretty soon, so I'm going to build a dedicated ~20-24 bay RAID6 storage server (w/ an Areca RAID HBA and maybe an HP SAS Expander) sometime next year.
I'm mainly going to use it for streaming media, as a TV server (DVB-C), web server and VMWare host (nothing too resource heavy though, mainly just to be able to run Linux and Windows on the same machine and to do some testing).

I'd like to buy one (or maybe a second) HDD now because I need some storage space to temporarily move stuff off my NAS to free some disk space.
I figured it'd be smart to buy the exact brand/model that I'm going to use for my build next year, so I could just throw it into the array as soon as the build is finished.

I'm currently trying to decide which brand/model/size HDD I should get.
I understand that Hitachi HDDs work very well with Areca RAID cards so I'm probably going with these, unless there are better options out there?

Then I have to decide on the RPM (not really relevant in such a setup?) and size, i.e. 2 TB, 3 TB or 4 TB.
2 TB seems a little small considering there's 4 TB drives out now, so it's most likely going to be a 3 or 4 TB. I wouldn't mind the higher price per GB for the 4 TB, as I'll only get one for now and the price is probably gonna drop a little over time anyway.

My main concern with such big disks is that, should a disk fail, rebuilding the array is gonna take significantly longer and the chance that more disks fail during the rebuild is higher also, right? Things like unrecoverable read errors and bit rot come to mind. I don't know too much about that stuff, maybe I'm a little too paranoid?
I suppose using 4 TB instead of 3 TB drives would be riskier than doing it the other way around though, right? (Again, this is in a RAID6 setup.)

So, what brand/size would you recommend I go for? Reliability and safety of my array are most important for me.


Thanks in advance for any help!

 

[xfataa]

Bump.

 

[GeorgeHR]

As you say the price is going to go down.

It does not really matter what drives you buy now. The cost is minor relative to the cost of the entire machine. (You will be buying 48 disks so you have a backup. Right?)

 

[Dangman]

Well first figure out which Areca HBA you're planning on using. Remember that not all Areca cards supports certain drive sizes and such. Some Areca cards don't support 3TB or 4TB drives. Some probably will support 3TB or 4TB but only if they're server class. etc.

 

[xfataa]

I won't be buying 48 disks, no. I will only buy as many disks at once as I require, and then update the array with new disks on-demand. I'll always keep a hot or cold spare though.

That's why security/safety of the data is my top priority (I know RAID is not a backup, but I can't afford 48 disks and I'm gonna keep backups of the more important data).

About the Areca HBA... I thought I'd decide on it based on which HDDs I'm gonna get. As I said in the OP, my main concern about 3 TB vs. 4 TB is the higher possibilty of a higher capacity dsik to fail due to an uncrecoverable read error (e.g. when rebuilding the array after a disk failed), or bit rot, etc..

Any more opinions? Thanks!

 

[xfataa]

Bump.

 

[Trepidati0n]

Most people only think drive cost and not "port cost" and "operational cost". For the typical small server...port cost is as high if not higher than the drive cost. In most cases, putting in the biggest drive you can is often the best course of action based upon the amount of space you need.

There are some odd variables here and there (bleeding edge drives, re-use HW), but on the wohle it is fairly true.

Simple example. Lets say you buy and HP Microserver and will use 5 drives in it. The box costs ~$400 when a good chunk of RAM is finally added which brings the port cost to $80. Lets say you needed 15 TB of storage and 2TB costs ~$60 and 3TB's cost $120.

Total for 3TB's = $400 + 5*$120 = $1000
Total for 2TB's = 2*$400 + 8*$60 = $1280

So, even though you paid less for the drives..you spent more on base HW and addtional operating costs.

---

 

[xfataa]

Most people only think drive cost and not "port cost" and "operational cost". For the typical small server...port cost is as high if not higher than the drive cost. In most cases, putting in the biggest drive you can is often the best course of action based upon the amount of space you need.

There are some odd variables here and there (bleeding edge drives, re-use HW), but on the wohle it is fairly true.

Simple example. Lets say you buy and HP Microserver and will use 5 drives in it. The box costs ~$400 when a good chunk of RAM is finally added which brings the port cost to $80. Lets say you needed 15 TB of storage and 2TB costs ~$60 and 3TB's cost $120.

Total for 3TB's = $400 + 5*$120 = $1000
Total for 2TB's = 2*$400 + 8*$60 = $1280

So, even though you paid less for the drives..you spent more on base HW and addtional operating costs.

---

Thanks for your answer.

I'm actually not really that concerned about the price. If the setup I want costs more, so be it.

What bothers me though, is that 4 TB drives are probably a little less safe than using 3 TB drives. Right? Or maybe I'm just a little too paranoid?

 

[drescherjm]

is that 4 TB drives are probably a little less safe than using 3 TB drives. Right?

I would say we can not conclude that. And if you are going for the same amount of total space having more disks in a single raid6 array (or raid 60 arrays) may wipe out any advantage 3TB drives would have over 4TB ones.

 

[Trepidati0n]

Thanks for your answer.

I'm actually not really that concerned about the price. If the setup I want costs more, so be it.

What bothers me though, is that 4 TB drives are probably a little less safe than using 3 TB drives. Right? Or maybe I'm just a little too paranoid?

You would have to assume that a 4TB drive is ~33% less reliable than the 3TB to make that paranoia true. If it was only 10%...I might give it to you. But 33% goes well beyond any reasonable math IMO.

However, if you plan on building a 20-24 port system right off the bat (cost be damned) then looking at drive cost and reliability does have more value.

 

[xfataa]

Thanks for your input.

Any more opinions maybe?

 

[Aesma]

I don't think RAID6 of 20 or more drives is really recommended. Also, I find strange that you would go from 4 1.5TB to 20 3TB in one go, it's a big leap !

 

[xfataa]

I don't think RAID6 of 20 or more drives is really recommended. Also, I find strange that you would go from 4 1.5TB to 20 3TB in one go, it's a big leap !

The 4 x 1.5 TB NAS is just one part of all the external storage that I'm using. It's pretty fragmented.

Oh and I wouldn't go straight to 20 x 3 TB, I'd probably start with 6 or 7 disks and expand when more space is required.
The reason why I want a 20ish bay solution is, that I want to be fairly future proof, i.e. being able to upgrade easily.

If RAID6 isn't recommended for that many disks, what would you recommend? Or, which amount of 3 TB disks in an RAID6 array is still safe?

Thanks.

 

[drescherjm]

If RAID6 isn't recommended for that many disks, what would you recommend?

Raid 60. Or multiple raid 6 arrays.

 

[GeorgeHR]

The 4 x 1.5 TB NAS is just one part of all the external storage that I'm using. It's pretty fragmented.

Oh and I wouldn't go straight to 20 x 3 TB, I'd probably start with 6 or 7 disks and expand when more space is required.
The reason why I want a 20ish bay solution is, that I want to be fairly future proof, i.e. being able to upgrade easily.

If RAID6 isn't recommended for that many disks, what would you recommend? Or, which amount of 3 TB disks in an RAID6 array is still safe?

Thanks.

Planning for the future is just plain guessing.

This month I just moved our server to a smaller case - drives have increased in capacity in the 6 years since I built the server. Our business needs changed (more disk files; less paper files).

I have been going to upsize my HTPC but I took out 2 hard drives. I can live with 8 hard drives of videos - 15TB today, 32TB is doable but note economical. So I wait until I run out of space.