sata RAID array vs 1 large IDE drive

mukki

I got MCE installed on a 10gig ide (xbox) harddrive, and then 2 sata drives in a raid array from all my recordings

everything works perfectly but....
i am thinking of swapping to 1 large 7200rpm ide drive for both the os and recordings, i want the raid array for my desktop

so does an IDE drive have enough bandwith to be able to record 2 shows (i have a pvr500) play another at the same time, and maybe have a few torrents running in the background, also its downloads folder is shared so the family and neighbours (wifi) sometimes play my avi's off it

8T8

IDE hard drive bandwidth shouldn't be the deal breaker but what kind of CPU you have is. Assuming the system has a decent enough CPU (ideally dual core) to handle all the simultaneous tasks you should have no problem recording two shows and playback of another at the same time.

Bittorrent isn't an issue either for ethernet or hard drive bandwidth assuming you have a wired connection to the PC from your router. If you are connected via wireless to to the router well using BT and playing XviD's over the WiFi network could be messy, depends on the quality of the router & how it handle's loads.

WiFi is definitely the bottleneck in terms of it's own bandwidth so too many people trying to use the wireless at the same time could be an issue so I would say that is the only thing to watch out for.

(Does the system have only IDE ports why not buy a SATA drive anyway)

SouperComputer

so does an IDE drive have enough bandwith to be able to record 2 shows (i have a pvr500) play another at the same time, and maybe have a few torrents running in the background, also its downloads folder is shared so the family and neighbours (wifi) sometimes play my avi's off it

Emmm, yes! I dont now how the idea that low res video is resource intensive got around.

The MPEG2 stream that MCE records at runs at 16Mb/s (Small b=bits not bytes) at most.

Most IDE drives peak at about 75MB/s (900 megabits) and should easily sustain 40MB/s (320 Mb's). So from that perspective you can see that you have a huge amount of overhead.

It should also be borne in mind that at lot of SATA drives are not actually any faster than IDE and infact use the same HDA (Head\Disk Assembly). Of course, RAID 0 them and you will max out ATA133 a little sooner than SATA2. But generally the drives are quicker due to changes in cache, parallel recording etc rather than the SATA interface.

mukki

SouperComputer wrote:

Emmm, yes! I dont now how the idea that low res video is resource intensive got around.

The MPEG2 stream that MCE records at runs at 16Mb/s (Small b=bits not bytes) at most.

Most IDE drives peak at about 75MB/s (900 megabits) and should easily sustain 40MB/s (320 Mb's). So from that perspective you can see that you have a huge amount of overhead.

It should also be borne in mind that at lot of SATA drives are not actually any faster than IDE and infact use the same HDA (Head\Disk Assembly). Of course, RAID 0 them and you will max out ATA133 a little sooner than SATA2. But generally the drives are quicker due to changes in cache, parallel recording etc rather than the SATA interface.

exactly what i wanted to hear thank for the help

8T8

Just curious SouperComputer but where did you see (or measure ?) that it requires 16Mb/s for recording MPEG-2 in MCE ?

I only ask as I saw this MCE DOC for system builders and it mentions this;

Per the following table typical TV encoding rates range from 2.4 MB/second to 9.0 MB/second.
Table 1: TV Encoding Rates
Recording Quality -- Approximate File Size (Encoding Rate)
High Definition -- 8.5 GB/hour (up to 19 Megabits/second)
Best -- 2.7 GB/hour (6 Megabits/second)
Better -- 2 GB/hour (4.5 Megabits/second)
Good -- 1.4 GB/hour (3 Megabits/second)
Fair -- 1.1 GB/hour (2.5 Megabits/second

According to that even at best (6 Megabits) which is the max for our standard definition TV it should till be perfectly manageable with two programs recording (12 Megabits) and handling playback unless I'm missing something here.

SouperComputer

Just curious SouperComputer but where did you see (or measure ?) that it requires 16Mb/s for recording MPEG-2 in MCE ?

Not sure TBH. IIRC is a max bitrate of some cards and was off the top of my head. So I was making a worse-case scenario.

quozl

My bog standard SATA drive combined with a pvr500 has no problem recording two streams while playing back another with a torrent going in the background.

My 1.3ghz via (junk) cpu also has no problem with all this as the pvr500 is a mpeg2 encoder so cpu usage is neglible.

po0k

You're sailing close to the wind. Keep one drive for recordings, and have one for torrents.

It's not a question of bandwidth, but capacity and mechanics. If you're accessing (reading/writing) to a few files on different parts of the one disk, the heads (which move as one) are going to have to thrash about to seek to the different sections of the disk platters. There is a rather low ceiling for that kind of work with a consumer-level disk.

More heads/drives means the machine is capable of more stuff going on - diskwise.

Trying to get one drive to deal with 3-4 or more sustained I/O streams (read and writing) will strain. Whatever about playback, you're recordings could suffer.

Besides, hard-drives rarely peak over 60MB/sec sustained transfer (from platter, not cache). The interface bandwidth is largely underutilised.
Run hdparm -Tt /dev/hd* under linux a few times and see.

Get a 6-8 channel hardware raid5 controller, PII/P3 system and a bunch of disks configured in 2 raid5 arrays (torrents and recordings), GigE controller and chuck it in the closet/garage.
Boot your MCE off a flash card/PXE boot and mount the remote share.

SouperComputer

Get a 6-8 channel hardware raid5 controller, PII/P3 system and a bunch of disks configured in 2 raid5 arrays (torrents and recordings), GigE controller and chuck it in the closet/garage.
Boot your MCE off a flash card/PXE boot and mount the remote share.

Have you done this with MCE SyxPak? Reason im asking is that the MCE live TV buffer is recorded to the OS HD (could be an issue running it from flash) and also getting it to record to a network share is messy with windows and a nightmare with Samba.

What you are saying about concurrent R\W's is correct, but in my experience consumer HD's are up to the job and TBH unless you plan serving 15 clients with a lot of data, RAID 5 is overkill.

Off the top of my head, I rememeber a couple of very "busy" MythTV setups, multiple tuner jobbies with bog standard drive configs, although I could be just nostalgic