RAID1, how many streams? vs. RAID10?

[Kremlar]

Looking to replace the aging RAID array in my HTPC server.

Currently running (8) Seagate 1TB drives in a RAID 6 array on an LSI 8708ELP RAID controller. Holds a variety of data, but most importantly my movie collection - mostly stored as MKVs. I have various HTPCs around the house that stream movies off of this server, perhaps 3-4 streams simultaneously max. Normally 0-2 streams. Not having any issues with the current setup - capacity and performance is fine.

I'm going to be rebuilding the server shortly, and the drives are getting up there in age so I'm looking to replace them, simplify a bit, maybe save some power. I've had a couple drives fail recently so I'm thinking it has served me well and now it's time to spend some money on it. I'd like to stick with some kind of RAID for redundancy - the though of re-ripping my media is not attractive. Any critical data is also backed up.

I'm going back and forth on 2 difference scenarios:

1 - Buying a pair of 6TB drives in the ~$250/each range and putting them in a RAID1 configuration.
2 - Buying 4 3TB drives in the ~$90/each range and putting them in a RAID10 configuration.

I think the 4x3TB configuration makes the most sense since it would be a bit cheaper and it would have a performance advantage, plus possibly increased redndancy, however I'm not sure if the performance advantage would matter for my use and I'd be powering 4 drives instead of 2. I know the power savings is pennies, but every bit helps - right?

Any thoughts? How many typical HD MKV streams can I expect to pull out of a modern drive RAID1 setup? I'm definitely leaning towards the RAID10 as I'm writing this.

For 6TB thinking of maybe these:
http://www.newegg.com/Product/Produc...82E16822178520
or
http://www.newegg.com/Product/Produc...82E16822236737


For 3TB maybe these:
http://www.newegg.com/Product/Produc...82E16822149408


I'd appreciate any other thoughts.

 

[soccerballtux]

3x6TB drives in parity configuration.

6TB drives will be good for a while to come. In 3 years you can add some more 6TB drives

 

[Kremlar]

3x6TB drives in parity configuration.

Out of my budget... And I'd prefer not to use RAID5 for such large drives, and do not like 3 drive RAID5 performance.

 

[dave_the_nerd]

4x 3TB would be faster, but for up to four streams, you won't benefit. A single HDD could handle that load.

Now, that said, the 2x 6TB would be much more expensive in terms of $/GB. So that would probably drop me back into the 4x 3TB camp.

There's no particular disadvantages to RAID5 in this circumstance, (or, rather, there is no particular disadvantage to RAID-5-ish software RAID like raid-z, mdadm or Windows Software RAID. Actual, honest-to-goodness RAID-5 has some things you might be concerned about.)

The write speed penalty for parity calculation is a moot point for video playback unless your server has a reeeealllyyy slow CPU.

 

[dave_the_nerd]

Out of my budget... And I'd prefer not to use RAID5 for such large drives, and do not like 3 drive RAID5 performance.

If 3x 6TB is out of your budget, don't get 2x. Budget based on the assumption that it will break and you will have to replace it out of pocket.

 

[Kremlar]

There's no particular disadvantages to RAID5 in this circumstance, (or, rather, there is no particular disadvantage to RAID-5-ish software RAID like raid-z, mdadm or Windows Software RAID. Actual, honest-to-goodness RAID-5 has some things you might be concerned about.)

The write speed penalty for parity calculation is a moot point for video playback unless your server has a reeeealllyyy slow CPU.

I'm not a fan of the performance hit of RAID5 writes and the rebuild times, though it's more of a convenience thing than anything as I don't frequently write lots of data to the array.

I will have to research software RAID as I've always been a traditional hardware RAID kind of guy.

Do you have any opinions on software RAID vs. hardware RAID as far as performance?

 

[Kremlar]

I went ahead and ordered 4x 3TB WD Red drives.

 

[Data-Medics]

Good choice going with the WD option. The larger Seagate drives have had a terrible reliability record.

 

[dave_the_nerd]

I'm not a fan of the performance hit of RAID5 writes and the rebuild times, though it's more of a convenience thing than anything as I don't frequently write lots of data to the array.

I will have to research software RAID as I've always been a traditional hardware RAID kind of guy.

Do you have any opinions on software RAID vs. hardware RAID as far as performance?

Performance will tend to favor hardware RAID, I cannot tell a lie. Although with a sufficiently beefy hardware setup, a software RAID can perform just fine, and with enough RAM and/or an SSD operating as a write cache, a server will do a pretty good job of hiding storage bottlenecks from the clients regardless of hardware/software RAID.

There is a question of "good enough" though.

The advantages of software RAID tend to be in the recovery (no RAID card BIOS fiddling, easy portability to a new system, hot swap in an array from another system and import without a reboot) and flexibility.

The flexibility part particularly matters for home users (cheap people) - you can, for instance, make a software RAID using multiple SATA controllers (a mix of motherboard ports and inexpensive SATA add-in cards, for instance.)

I would also point out that most of the big datacenter SAN systems are, by necessity, using some sort of software abstraction - otherwise they couldn't store data across multiple racks of HDDs, multiple SAS controllers, etc. So it's not like the technology isn't there, it's just that for small and medium business servers (<12 HDDs), there's not much to differentiate hardware and software RAID. So the older guys swear by hardware RAID cards, same as they've always used, and the n00bs don't.

 

[Cerb]

I'm not a fan of the performance hit of RAID5 writes and the rebuild times, though it's more of a convenience thing than anything as I don't frequently write lots of data to the array.

The performance hit is just that you get speed slightly slower than a RAID 0 of n-1 drives. Rebuild times are usually long enough to make you want to back up, instead. With video, random performance will be a rare thing to need to worry about (you'll get nothing against RAID 10 from me, though)

Do you have any opinions on software RAID vs. hardware RAID as far as performance?

In Windows, hardware RAID, every time. In Linux, software RAID is almost always faster, unless needing hardware RAID for a special system, like VMWare, or are comparing file system specific features (ZFS' parity RAID can be slower than LSI RAID 5, FI). RAID itself is not particularly processor intensive, parity RAID included, hardware RAID just remains popular due to its ability to abstract the RAID away from the software using it. It also makes hot-swap and such easier. But, with a good hardware RAID controller, the difference will be pretty small, and the HDDs themselves will be the main limiting factor.

Performance-wise, you should just need RAM. A single drive aught to be fast enough all by itself. Tasks other than video handling could be noticeably faster with a RAID 10 of 4 drives, though, such as incremental/rolling client file backups.

 

[Kremlar]

Surprise! I had decided to go with RAID10 on my LSI 8708ELP controller. Started the upgrade last night and after troubleshooting some unrelated issues (corrupt Windows Server 2012 R2 ISO download) it turns out that RAID controller does not support drives greater than 2TB!

So, I ended up using the Intel ESRT2 integrated into my server board (S3420GP). I researched Storage Spaces and everything I've read is that performance is low. Although I don't need huge performance, I want to get the most out of my hardware and would prefer to go with RAID10.

I went with ESRT2 over Intel RST/Matrix because I prefer the RAID management software for ESRT2 (I can use the LSI MSM) - supports email notifications, etc...

I haven't benchmarked anything, but "seat of the pants" performance seems good. I restored about 2TB of data over USB3 to the array in less than 5 hours which seemed decent.

Thanks

 

[Kremlar]

Correction on that. It was about 1.7TB of data.