HTPC - stripe or mirror?

[Foo]

Foo, what hdd's? and what was the connection to the card? fiber?

20 x Sata II 1Tb drives at about $150 a pop

4 x 4-to-1 Sata Multiplier Cards

1 x 4-to-1 Sata-to-multilane adapter

1 x 1-to-4 Multiplier-aware RAID card

So SATA all the way to the server. The contention is in card performance plus cramming 4 cards into each 3Gb/sec sata channel.

This isn't a SAN you should host production VMs off, but it looks like it'll make a decent flat file store or 'tier 3' SAN space.

Serve it up with Openfiler on the host server and maybe a quad-port NIC....

[AmIdYfReAk]

I've never seen those Multiplier cards before.... they work decently?

[Foo]

I need to get one in my hands and test it. Waiting for a good opportunity to piggy-back one of these setups into another order (we always need more capacity).

From what I've read, they work fine but the controller at the end of the chain has to be multiplier-aware.

If the throughput is reasonable then something like this seems ideal for nearline storage. I doubt it's fast enough for backup staging but for stuff like old user files, psts, archived vm disks..... should be ideal.

[Dr_Watson]

Depending on the raid controller in use you may get nearly as high performance from a RAID 1 mirror as you would from a stripe, the only thing you'd be losing is the extra capacity.

Some (citation needed) RAID 1 mirrors on modern controllers can do the 'read/write alternate blocks from alternate disks' technique to get higher performance on RAID 1 just as they would on RAID 0.

read performance is equal to raid0
you still take a write penalty because the controller can't do any wizardry to stop the fact that the data needs to be written twice.

[Dr_Watson]

How much space and how many drives are we talking here?

I'd probably get three of these and go RAID5. That way, you get one drive worth of fault tolerance but you can easily grow the size of your partition. If you're really going crazy with a large number of drives I'd go RAID6 but I doubt any desktop mobos offer it.

Why raid edition: http://www.wdc.com/en/products/products.asp?driveid=335

Raid5 = bad idea
you take a write penalty on raid5 (and even higher penalty on raid6) from the parity calculation
for performance concerns if you're writes will exceed 25% of total IOPS but you want protection do raid 1/0
if you don't need protection go raid0 and just implement some sort of backup solution

[plained]

streaming and servers and all that eh

i like wd tv type things

[Dr_Watson]

FYI, if I was putting in an HTPC i would put a small SSD for the operating system and put the mass storage in a closet file server.

if you're HTPC boots from SSD and has no other internal storage it keeps the unit compact and quiet. You also don't need to have a fancy motherboard with lots of on-board shit, just something fit for your processor with enough expansion for 2 capture cards and a TOE card.

Then you can build a fat file server that sits in a closet allowing you to not only add storage whenever you want but run a very good RAID card with lots of high-speed protected disks.
With gig/E and iSCSI on a FreeNAS or OpenFiler (free NAS box BSD based operating systems) you can have lots of local disk presented to your HTPC and also share the content you download with it or what it records with other PCs

lots more performance and flexibility.

[R00k]

If you already have a lot of your media ripped on a different drive somewhere, I wouldn't worry too much about write performance. Almost all of what you will be doing will be reading, except when you pick up something new -- and then you can just start it and walk away.

If none of your stuff is ripped yet, write performance may be a stronger consideration.

I'm virtualizing around 60 servers over the next 3 months or so here at work, and I'm already trying to figure out a way to take a couple of them home for media storage.

I think in my ideal setup, I'd have a Media Center PC that runs as lean as possible (w/ a separate pagefile disk), and all the media sitting on a dedicated server connected via gigabit. Preferably running RAID5. Then maybe back both of them up to a cheap NAS box (or even a USB drive) using NTBackup, for recoverability.

[Dr_Watson]

write performance is a big deal if you're doing TiVo style time shifting and recording... which is kind of the whole point of an HTPC. If you're just streaming media get a playstation or xbox.

[R00k]

Good point.

Still, short of buying a lot of disks and wasting a lot of space on parity/redundancy, it's hard to get decent availability (i.e. lose a drive and still be running) without going RAID-5.

Don't get me wrong though - I'm certainly not trying to sound like an expert. I don't even have a tivo, much less and HTPC at the moment. I know quite a bit about storage solutions, but I don't know much about media center performance.

I know that the difference between RAID-5 and RAID-10/01 is huge on a heavily-used enterprise server.
I'm a little skeptical that it would be that noticeable on a machine playing or recording video files, but that's nothing more than an uninformed assumption.

[Fender]

I might have to go w/ a 1+0 or 0+1 solution. Dammit... dunno.

I'm not really interested in doing my own timeshifting, our DVR does a good job w/ HD and has enough room. I just want to have all my movies available w/ out the physical media being scattered all over the family room. Also having our music, pictures and home video stored on my laptop and on the network as backup is a big plus.

[R00k]

RAID5 or even 6 should be fine for that, IMO, as long as you have decent disks and controller.

It's hard for me to imagine that streaming static media files for a home theater would be more demanding than some of the things we run on RAID-5 at work.

Buying twice the number of physical disks that you need for space seems a little overkill to me.

[Dr_Watson]

if that's all your doing I'd honestly just get a ps3 and run tversity on a windows pc full of hdds in a closet.
share pix video and music on wifi to the ps3 or laptop or iPod etc
tversity is free; windows is easy; wireless is versatile; and the playstation is a be player
you don't need the expense and hastle of an htpc
oh I hear it plays HD video games too

[Fender]

But at that point I still need a windows pc full of HDDs in a closet. I don't think I've save much cash, either. And the new PS3s can't run Linux, if what I've heard is true. I already have a 360, though...

[Dr_Watson]

if you already have a 360 that is certainly the cheapest and easiest way to go

[Fender]

How do you figure? I still need a PC (MB/CPU/RAM/video card/PSU/case), a BR drive for ripping, and a bunch of HDDs. I don't have Ethernet wired in my house, either, so I wouldn't get to hide the storage box away. It would need to be physically close so that it shares the network switch that the 360 and blu-ray player use for wireless internet access.

[Dr_Watson]

you dont need impressive hardware, special equipment, or have to make compromises

[Fender]

Anyone know of a decent mini-ITX case that supports a full sized optical drive instead of a slim drive? PSU is optional.

hmmm... maybe this or this. That's a TINY case, but I'm not convinced it will handle a non-slim/slot optical drive.
edit2: yeah #2 is slim optical only... i think... fuck... maybe?

[l0g1c]

I'm going to say drop the RAID idea. I have a 4-year old PC serving as my HTPC right now. No RAID, and I use it to record two NFL games concurrently in HD every Sunday without issue.

As someone already stated, RAID is not acceptable as a backup solution. Honestly, I'd buy a blu-ray burner, get your full backup of your media done and then set it up to do incremental backups once a day or week or whatever.

I understand why on its face, RAID seems like a good idea. Performance and redundancy, right? I say spend your money on a nicer drive (even 10k rpm disks don't sound like jet engines anymore) and a blu-ray burner. You'll probably still save money and have a better solution than RAID.

Edit: to be clear, the blu-ray discs in this equation are only acting as backups in case of HDD failure. By doing an incremental backup, you're only backing up the changes and shouldn't go through too many discs after your initial backup. You can set up a directory to hold the movies you rip and exclude it from the backup process, since you obviously already have a backup for them.

[phantasmagoria]

you dont need impressive hardware, special equipment, or have to make compromises

Indeed, in fact if you talk to your local university then most of them run schemes where they sell their old hardware (minus HDDs) for next to nothing, because the alternative is they dump it in a skip. I ran a server for ages which was a computer I got from uni that they were throwing out.

[R00k]

...

Home-burned CDs and DVDs aren't good backup solutions because they go bad. You can prolong their lifespan, but you have to take quite a few hassling precautions, and even then it would be hard for me to really have confidence in them.

There is another way to get reliable backups. Buy 3 times the number of disks you need (if you need 1tb, buy 3 1 tb disks). Leave one out of the computer, and set up the other two in a hardware mirrored pair. Every month or so, pull out one of the drives and replace it with the one on your shelf. That way you'll always have a copy of your data on the shelf. You also get the added benefit of not having to use any sort of software, never having to restore anything, etc. If you need to restore the previous backup, you just take all drives out of the box, put your backup drive in and boot to it. Everything works.

The downside is the added cost - you're wasting an entire disk. But for a single solution that covers availability, recoverability and performance it's hard to beat. You also have to be able to buy a single drive that covers your capacity needs.

[Fender]

I'm not worried about making backups of the DVDs/Blu-Ray disc I rip. I'll have the original media for those. All I need to backup is our MP3s, pics and home vids. Several hundred MB at most. I'll probably just do an automated backup of those items from my laptop to the HTPC. Then just keep adding drives to the HTPC as needed, eventually going to an external enclosure running JBOD.

[^misantropia^]

There is another way to get reliable backups. Buy 3 times the number of disks you need (if you need 1tb, buy 3 1 tb disks). Leave one out of the computer, and set up the other two in a hardware mirrored pair. Every month or so, pull out one of the drives and replace it with the one on your shelf. That way you'll always have a copy of your data on the shelf. You also get the added benefit of not having to use any sort of software, never having to restore anything, etc. If you need to restore the previous backup, you just take all drives out of the box, put your backup drive in and boot to it. Everything works.

Not even that is entirely safe. If you are doing hardware RAID you'll need identical drives (up to the firmware version, often) so they will have the same MTBF. If I got a nickel for all the times drives died in a cluster almost simultaneously, I'd have... well, a few nickles at the very least.

It depends on how much you value your data, I suppose. Losing a bunch of MP3s is a nuisance but no more. Your company's financial records less so.

[R00k]

I don't know how many BR movies you have, but I expect your collection will keep growing.

The thing is, once you get a lot of them ripped, and if your drive fails down the road, you'll then be looking at spending a LOT of time ripping them all again. When you have that much data on a box, and it fails, the prospect of losing and having to recreate all of it is depressing, especially when you realize you could have spent just a little more cash and had a backup.
You'll be looking at the choice between spending dozens of hours ripping all your movies again, or just not bothering. But you can't just not bother, because then you would have wasted the time and money you spent on the system to begin with.

I speak from experience -- not with a HTPC, but with other data. I also know several other people who have put a lot of time into creating a media library at home, and lost it all, and just decided to say fuck it, and watch all their movies from the disks going forward. Because once you get to that point, you realize that having the library is just a "nice to have," but not necessarily worth all the time and trouble it is going to take to recreate your system.

My advice would be to put in the extra time and cash up front, and you'll never have to worry about that.

[R00k]

Not even that is entirely safe. If you are doing hardware RAID you'll need identical drives (up to the firmware version, often) so they will have the same MTBF. If I got a nickel for all the times drives died in a cluster almost simultaneously, I'd have... well, a few nickles at the very least.

It depends on how much you value your data, I suppose. Losing a bunch of MP3s is a nuisance but no more. Your company's financial records less so.

That's not true. I've had to replace drives 3 times in servers in the last week and a half, and in two of those cases I replaced them with drives that were from a completely different manufacturer. To any decent modern RAID controller, all that matters is that the disks are the same size and have the same performance specs.

Also, your example of multiple drives dying in a cluster, while valid, doesn't apply so much here. The odds of having multiple drives die in a system increases with each additional drive you have in it. If you have a cluster/storage group with 50 physical disks in it, your odds of having more than one drive fail are exponentially higher than if you had a system with two disks.

The mirrored + spare system vastly decreases your odds of having a non-recoverable failure, for a few reasons. First off, there are only two disks, so your odds of having two fail at the same time are low -- but even if you DO have two disks fail at the same time, it doesn't matter, because you still have a perfectly good, bootable drive sitting on your shelf that has everything on it except what you've done in the last few weeks.

Second, since you are deciding when to pull a drive for backup purposes, that means that you will only be pulling your backup at a time when you know your system is good and your data is intact. That is the upside to not being automated. If you use an automated/scheduled backup system, you have a very real chance of backing up corrupted data, and therefore not being able to recover it.

The only real disadvantage to the mirror + spare system is that you are wasting a whole disk and also that, in order for it to work, you have to be able to fit all your data onto a single disk (unless you want to buy a bunch of disks and get really complex, like a cycling mirrored set of stripes for instance).

Since the disk is on a shelf, you don't have to worry about corruption, power surges, etc. It's a good system that doesn't take much work to setup. Just make sure you shut down the machine before you pull out your spare drive (even if it's hot-swappable), so you don't get any corrupted files from interrupting disk activity.