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HTPC storage question

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September 19, 2011 1:38:45 PM

I'm seeking to build a HTPC, but this is my first build; while technically capable, I have no experience of specifying individual components in a machine having, up until this time, bought pre-built systems. While I'm able to get a general idea of the overall performance of a machine (having kept myself up-to-date on the latest hardware releases via Tom's Hardware for the last few years) I've no idea whether individual components are capable of what I need them to do, or whether they are just overkill.

As previously mentioned, I'm intending to built a HTPC; however, all it really has to do is be a media server. I have almost 700 DVDs that need to be stored on hard drive for easy access; I've calculated that, assuming an average of 7GB per disc, I will need 6TB of storage. In the future I will probably replace these DVDs with Blu-ray versions, so I might end up pushing the storage much higher.

As a 'green' hard drive is, in the UK, often half the price of a comparable 'performance' drive of the same capacity and, as I want the energy consumption to be as low as possible, I would prefer to use 'green' drives in my build - especially as I want to keep the price as low as possible. That said, you can see my inexperience showing, as my question is: are so-called 'green' hard drives made by Western Digital / Hitachi / Seagate fast enough to be able to serve a single Dolby Digital or DTS audio & 1080p video stream to a connected TV / home theatre receiver?

Any comments to help a novice would be gratefully received!

More about : htpc storage question

a b G Storage
September 19, 2011 2:25:24 PM

The green drives would be plenty fast for 1 machine to stream from it, and probably a few more would be fine as well.

Do not buy WD drives if you plan on using any form of Raid config for these.
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September 19, 2011 2:38:08 PM

Thanks, Ubrales and tomatthe, for your replies!

My intention was to get 3 x 2TB drives as 3TB drives are pretty pricey at the moment. Originally I'd thought about just having these three drives, but I may have a small boot drive as well.

I've looked at some reviews on Tom's of green drives (most recently the review of 3TB drives on 8th September), but I'm unsure how to interpret the data.

To my mind, even the slowest green drives are able to sustain at least 50MB / sec as the bare minimum, which I would have thought ample for a sustained sequential transfer of an .iso image off a hard drive; after all, it can be read off a regular DVD without jumping. In the same way, a full-HD film and audio can be played by a Blu-ray player without missing a beat. According to wikipedia - though I can't attest to the reliability of information here - a DVD only requires 1.39 MB / sec to play back. At 24x, a DVD drive only achieves 33.24 MB / sec (though of course I wouldn't be watching the movies at 24 x speed!). Likewise, a Blu-ray required 4.5MB / sec, rising to 54MB / sec at 12x speed.

Is my information and logic sound?

Ubrales: I take your point regarding the reliability; obviously this would be an important consideration. However, could this be offset slightly by using RAID 5 on the drives?

tomatthe: I hadn't particularly thought of RAID; my initial feelings were JBOD to be honest. If I was heading to RAID I was leaning towards RAID 5, as I didn't want to lose any of the disc images after it taking weeks and weeks to convert them all! Is there an issue with WD drives and RAID? I was intending to use Ubuntu Linux with the build; is the issue OS dependent or not?
a b G Storage
September 19, 2011 2:44:16 PM

No WD drives will work properly in a Raid set except for the RE editions which are much more expensive. They changed some things in the firmware around Jan 2010, and since then they do not function properly, as in they will drop out of Raid sets repeatedly.

Issue would exist regardless of OS choice.

If you are going with JBOD this wouldn't matter, but for an htpc you might want to think about a Raid set to allow for larger volumes without having too many diff drive letters.
September 19, 2011 2:48:50 PM

tomatthe said:
… for an htpc you might want to think about a Raid set to allow for larger volumes without having too many diff drive letters.

Thanks tomatthe.

Would you recommend any particular RAID level? Obviously RAID 0 would be best for performance, but would RAID 5 be overkill? Would it have any effect on overall performance?
a c 119 G Storage
September 19, 2011 2:55:43 PM

spaceman_spiff said:
Thanks tomatthe.

Would you recommend any particular RAID level? Obviously RAID 0 would be best for performance, but would RAID 5 be overkill? Would it have any effect on overall performance?

Definitely not RAID 0! In RAID 0 (striping) loss of one disk loses all data! Beware of 'striping' in any RAID configuration!

The WD Caviar Blacks are fine for RAID and are very reliable. I have RAID 1. Same with the Seagate I listed. Both brands, multiple drives, running without a hiccup for over 20 months.
September 19, 2011 2:58:31 PM

I have a SSD as the system drive and green drives as storage on both of my PC's. I used my main PC to stream media for a couple of years without issue, and then built a seperate HTPC/server and upgraded my storage about a year ago.

Instead of using JBOD I used the library function in Windows 7, since several users warned that it can sometimes be difficult to recover a JBOD array if one drive fails. I also stayed away from RAID for the same reason and just used sync software to back everything up. RAID 5 was an attractive option but seemed like extra hassle to me.

Personally when I look at storage drives I only look at capacity and then the reviews to check reliability.
September 19, 2011 3:09:44 PM

Thanks Umbrales & zaho0006 for your help.

Umbrales: I realised the potential for data loss with RAID 0 so, while I was aware of the performance benefits, I wouldn't go that way due to the risk of losing data. Would you consider RAID 5 overkill for a simple HTPC / media server? Due to the amount of storage I require, and the limited budget I have, it wouldn't be practical for me to run the disks as RAID 1 - but I could probably stretch to another drive and implement RAID 5. I've noticed that some motherboards have hardware RAID capabilities - would it be better to use these, or rely on the OS software RAID capabilities (in this case, Ubuntu)?

zaho0006: Did you have any problems using green drives for serving up video media? I understand that there is a similar function in Ubuntu to the library function in Windows 7, and I had thought about using this in the absence of a RAID setup, for convenience.

Backing up is not going to be practical for this build as I simply can't afford to buy an extra 3 drives. However, I guess I would still have all the original DVDs so I could just recopy them over - but it would just take an awful long time to do it …

As you can see, the specifications of this build are all up in the air at the moment! I've thought about a lot of different ways of organising the storage, but I needed to run it past people who have a lot more experience at system configurations and home building than I have!

Thanks to all for your help! :D 
a c 119 G Storage
September 19, 2011 3:39:36 PM

Since you plan on keeping the original DVDs, RAID 5 might be the way to go. 1 disk fault tolerance.
September 19, 2011 3:49:59 PM

Ubrales said:
Since you plan on keeping the original DVDs, RAID 5 might be the way to go. 1 disk fault tolerance.

I guess that would be the ideal, without having a backup (though I realise a backup is always better). Are there any performance penalties using RAID 5? Would hardware RAID 5 (i.e. a feature offered on the motherboard) be better than a software RAID 5 (i.e. OS implemented), or is there a performance penalty irrespective of method?
a c 119 G Storage
September 19, 2011 3:54:29 PM

spaceman_spiff said:
I guess that would be the ideal, without having a backup (though I realise a backup is always better). Are there any performance penalties using RAID 5? Would hardware RAID 5 (i.e. a feature offered on the motherboard) be better than a software RAID 5 (i.e. OS implemented), or is there a performance penalty irrespective of method?

No type of RAID is a substitute for backup! Definitely backup the disk containing the OS and programs on a regular basis.

As far as RAID is concerned, I use on-board RAID on my EVGA motherboard. Almost 2 years without any problems of any kind.
September 19, 2011 4:02:06 PM

Thanks for your help Ubrales!

I've just been reading the RAID forums and it seems the general concensus is that, unless you use a specific RAID card (as opposed to a motherboard and / or software controller) RAID 5 is not a good idea - their advice is either RAID 0 or 1.
a c 119 G Storage
September 19, 2011 4:07:33 PM

spaceman_spiff said:
Thanks for your help Ubrales!

I've just been reading the RAID forums and it seems the general concensus is that, unless you use a specific RAID card (as opposed to a motherboard and / or software controller) RAID 5 is not a good idea - their advice is either RAID 0 or 1.

I use RAID 1 and I backup frequently.
September 19, 2011 5:08:13 PM

Thanks for all your help Ubrales! I've got a better idea which way I need to go now. I just need to save up a little more than I previously thought ;) 
September 19, 2011 5:21:26 PM

I recently built a file/backup server based on an Intel Atom D525 (gigabyte's board to be exact) and I used two Western Digital Caviar Green drives. The OS is loaded on a 8GB CF card with a PATA adapter.

Your bitrate numbers seem to be correct. When watching network usage while streaming DVDs the stream is typically around 15Mbps or 1.87MBps. Accounting for some network overhead that is very close with your DVD specs. I've also played HD content (I believe 1080i 60FPS) from my camcorder and it plays perfectly. I know I can easily break 40MB/s when backing up large files via Samba.

As for the Western Digital Green drives, as noted they aren't good for RAID setups. They also have one other drawback in that they cycle the heads a lot. This is supposed to be to save power, but from what I can understand it happens to frequently in Linux and there is no easy way to change it (there is special WD software). My solution was to put the drives into sleep mode after X minutes of disk inactivity, but some Ubuntu updates are causing the disks to be constantly used. Luckily I have an old image and I plan on going back to it and just not updating. With the disks spun down except when in use they are good drives. I'd consider another brand unless they are the cheapest and you don't mind messing with them.

As for RAID, my opinion is that you should avoid it, since it isn't a backup solution, and it really isn't needed for home use. I prefer to run individual disks with individual nightly incremental backups (no RAID 1). With RAID 5, you are likely to see a complete raid failure before completing a rebuild of the RAID, and to me it isn't worth losing all my data compared to one disk of my data (if it wasn't backed up). Also, since you are only talking DVDs, there is little reason to run RAID or backups. Yea, if you lose a disk it'll be a pain to rip 2GB of movies, but it is a question of cost vs. convenience.
September 19, 2011 6:37:49 PM

Thanks nordlead, that's very helpful.

It seems from your post that you are running Ubuntu on your server? Was it easy to set up, and do you believe it would work OK if I used Ubuntu on my htpc (I'm intending to use XBMC as the front-end for my media)?
September 19, 2011 8:16:38 PM

spaceman_spiff said:
Thanks nordlead, that's very helpful.

It seems from your post that you are running Ubuntu on your server? Was it easy to set up, and do you believe it would work OK if I used Ubuntu on my htpc (I'm intending to use XBMC as the front-end for my media)?


Yes, I'm currently running Ubuntu Server 11.04 with Webmin as my interface (although I do ssh into it just as often).

Ubuntu can either run XBMC or run a Samba share to share files with another PC running XBMC. I've only goofed around with XBMC a tiny bit before dumping it for WMC, but Ubuntu is a good option as an OS since there is a lot of support for it. If you set up your PC correctly (OS+Programs on boot drive, data on data drives) you can always try Ubuntu first and if you want to switch to another OS just image your OS first and try something else. I'm thinking about trying Openfiler myself, but for media capabilities there are a few Ubuntu based options like LinuxMCE and MythBuntu.

Setting up Ubuntu as a server was fairly easy considering I had minimal Linux background. I've used a Sun workstations and I've setup Ubuntu & Fedora on my laptop 5 years ago, but I'm mostly a Windows user. Granted, I'm a software engineer by trade so I knew what I was getting into and have no problem pouring through web pages to figure out what I need. I probably spent more time tweaking settings to get my power consumption to as little as possible than it was worth, but I learned a lot in the process.

I did have one problem getting Samba up and running, but that is because Windows (HTPC) and Ubuntu (laptop) as clients don't play nice with the Samba server unless you get the settings right. If you just have Windows or just have Ubuntu clients it is easier to setup.

As for picking hardware, I highly suggest you write down your priorities for the system first then decide on parts. From the OP i have a feel for what you want, but it isn't clear. For me it was low power, file/backup server, capable of holding 8HDDs (with extra PCI cards), cheap, flash based boot drive and so on in that order. Once you have those you can pick a few components and read reviews to see if they meet your needs. If you post your list of requirements here I'm sure people will help find the right parts for you.
September 19, 2011 8:41:58 PM

Thanks once again, nordlead.

Part of the difficulty is I haven't tied down my specifications yet, as I was just getting a feel for what's required and dipping my toe in the water before dropping any cash on something then regretting it later.

I'm going to try getting my hands on an older PC from work which is surplus to requirements, and then I'm going to load Ubuntu on it and just play around with it to make sure I can do all I want to. I think one of the major issues with the whole project is just how long it will take to copy almost 700 DVDs onto disk: after playing round, I may discover that it would take too long to copy them to be a practical solution.

That said, I especially appreciate your comments about getting the specification of the build sorted first, then I can get help finding the right components for the build. Sounds like good advice to me! :) 
!