Recommended drives for 15 bay DAS for backup server

[thething55]

I am currently in the process of planning my new backup solution for home so that I can backup all of my laptops, desktops, computers and servers etc. I looked at NAS drives and even SANs but all of these felt very expensive for what you are getting so I have decided to go with a DAS which will hook up to one of my servers using a PERC 5E or preferable a PERC 6E . Anyway, I am planning on picking up a MD1000 which has 15 bays along with a raid controller, cables and drives.

 

I am thinking that I would like between maybe 10TB and 15TB of usable storage in a raid 6 (using a perc 6) or a raid 5 (if I end up with a PERC 5)

I am just wondering what everyone thinks I should use in terms of drives. WD red 3TB drives seem to be the cheapest per gigabyte for WD Reds in the UK but I am open to other manufacturers providing that they have a good reputation

 

I fully understand that I don't want the cheapest drives for something like this but I wanted to see if anyone else had some other drives in mind which would be good for the job. I am currently looking at a bundle on Overclocks for 3x3TB for £262 so I could pick up 2 bundles of these for about 12TB of raid 6 storage. I also understand that a RAID 6 might be considered a little extreme for home use but if I am depending on this to backup my entire life then I want a little extra security.

[tt2468]

WD Red Pro

[KirbyTech]

Seagate Enterprise drives are great, check out the price on them also if you want 10tb now what about in 2-3 years plan for then not today.

[paddy-stone]

Personally I wouldn't trust my entire life to one device anyway... For me it is preferable to backup to 2 locations ie NAS and external storage, at least that way there is a lower risk of both devices failing simulataniously. But again it's a preferance that is personal and depends on how much time you want to employ doing the 2 backups.

[Djole123]

WD Reds or WD Purples.

[tt2468]

3 minutes ago, Djole123 said:

WD Reds or WD Purples.

WD Purple is for surveillance applications. It would not do well in a raid configuration, or in a nas in general.

[Djole123]

2 minutes ago, Kyle Manning said:

WD Purple is for surveillance applications. It would not do well in a raid configuration, or in a nas in general.

Oh my bad.

[thething55]

WD Reds still seem like the way to go then. I typically Avoid Seagate drives these days since I haven't had great luck with them in the past but maybe they've improved or was I just unlucky back in the day? If I am going for WD reds then I think I will just go for standard REDs since I can't justify the cost of RED pros and RAID 6 should protect me against data loss from failed drives (hopefully!) and I think that the chance of me losing my primary copy as well as 3 drives from a raid 6 is highly unlikely but I do have a small online backup for my really important stuff if that somehow happened.

 

When it comes to future proofing I will just add more drives to the array as I suspect that I will only end up using 6 out of the 15 drive bays.

 

Thanks for your options, I think I already knew the answer deep down but I just wanted someone else to confirm it.

[Blake]

2 hours ago, thething55 said:

WD Reds still seem like the way to go then. I typically Avoid Seagate drives these days since I haven't had great luck with them in the past but maybe they've improved or was I just unlucky back in the day? If I am going for WD reds then I think I will just go for standard REDs since I can't justify the cost of RED pros and RAID 6 should protect me against data loss from failed drives (hopefully!) and I think that the chance of me losing my primary copy as well as 3 drives from a raid 6 is highly unlikely but I do have a small online backup for my really important stuff if that somehow happened.

 

When it comes to future proofing I will just add more drives to the array as I suspect that I will only end up using 6 out of the 15 drive bays.

 

Thanks for your options, I think I already knew the answer deep down but I just wanted someone else to confirm it.

One thing you might want to consider, is that with 3TB drives that have ~1 in 10¹⁴ Non-recoverable read errors per bits read in RAID 5, you only get a ~22% chance of recovering your array if a disk fails. if you get the WD Pro drives that changes to ~1 in 10¹⁵, and 86.3% to rebuild.

 

RAID 6, while it will give you the added protection, you wont find it recommended on drives above 2TB, and RAID 5 above 1TB.

 

Normally I don't care about this sort of thing (my home server is even worse 4x6TB in RAID 5 or ~14% chance to recover after a disk failure), but you'd mentioned this is for backups.

 

I'd double check that the PERC 5E\6 supports dynamically expanding arrays, I'm not a Dell guy, but I know HP's servers do support this (so I assume it does).

 

 

 

 

 

[thething55]

You bring up a good point about non recoverable read errors and raid 5/6. I knew about the risks with this sort of setup in raid 5 but I didn't think about it for RAID 6. I think I will need to go over all of the math tomorrow and work out an acceptable risk for the array.

[leadeater]

For that many disks WD recommend Red Pro or Se. Seagate Enterprise NAS disks are also good option.

[leadeater]

2 hours ago, Blake said:

I'd double check that the PERC 5E\6 supports dynamically expanding arrays, I'm not a Dell guy, but I know HP's servers do support this (so I assume it does).

Ignore, miss read your post 

 

Edit:

Also most vendors use LSI as the OEM for their RAID cards. HP recently switched to PMC Adaptec from Px10 series onward, everyone else still uses LSI. LSI support dynamic expansion so any card based on them will too, you can also cross flash cards between vendor firmware or to native LSI. 

[thething55]

I have one more major question, until now I have only used raid 10 at home and I have never had to deal with a raid 5/6 rebuild.

during the rebuild, what happens if a drive hits a URE? I know the rebuild stops in failed state with raid 5 but what happens in raid 6?

Also, is it possible rebuild again or will a failed URE destroy the array and make it corrupt/unrecoverable?

Until now, I thought that a URE on a raid 6 would swap to the other drive for the parity info.

Does anyone know of any good sites that explain raid 6 and its parity and URE on good detail?