Does HD Cache size matter for capturing?

[jennyandgreg]

From everything I can tell it seems to me a larger cache (new 8 megs versus the older 2 megs) means nothing for video capturing. Seems to me that with capturing you are doing a constant stream of data into the drive and not little read/writes where a cache would help.

Is my logic correct here?

[Karate Media]

Isn't a large, long, constant stream of data when you DO what more cache? It's to stop the bottleneck, right? That stream of data is just gonna keep on coming, and something has to deal with the overflow if the drive gets stuck writing a particular piece of data.

I would think, then, the more cache, the better, especially for video...Am I wrong?

[jennyandgreg]

Think of it this way, a cache is there to "hold" data thats accessed often. If you start downloading say a 20GB file to a drive its going to e a long stream of constant data. There is no recurring use of data as its all going one way.....into the drive.

Where a cache helps, as I understand it, is where your PC is constantly going back and forth pulling data to and from the drive. In that case the cache holds data thats repeatedly used to speed access.

Thats my understanding at least....looking forward to hearig from an expert here!

[K2]

The cache is No help.

[dcsos]

No you do not want a larger cache size in capturing

Look from the VIDEOGUYS:
they tell you how to disable even the 2 megabyte cache that comes with most drives..eg donot use write behind cache while capturing video
you may drop frames
Under Windows, go to Settings/Control Panel/System, click the "Performance" tab, and click "File System". There, you will find "Read ahead optimization" set to "Full".
Change it to "None".
Then click the "Troubleshooting" tab and put a check mark in the
"Disable write-behind caching for all drives".

We don't want the drives to read ahead, look behind, or do anything except read and write the video data stream.

[jennyandgreg]

No way to turn off the cache on specific drives huh?

[Karate Media]

I'm still confused on this one...I've been looking at new harddrives and it seems to me that most of the suggestions I've read have recommended a higher cache. In fact, in doing a double-check on the dv.com forums just now, another person used a similar analogy to my "bottleneck." And no one seemed to be against 8MB of cache, in fact a number of people recommended it. I have read other positive things about using a higher cache for video work, but I did the quick check w/ dv.com b/c I tend to find fairly reliable POVs there...

Admittedly, people at dv.com are also doing a lot of editing, so they may prefer the higher cache, but they are also capturing video, of course, and no one even recommends turning off the cache for capturing. A quick google search didn't turn up any negatives either (true, I did a quick search...).

I've certainly never had any problems capturing w/ a 2MB cache -- but should I save $$ on my second (internal) HDD by not getting 8MB?

Can anyone else offer some specific cites (and sites) where I can read more about the negative effects of 8MB cache on video capturing/editing?

[Xtasy2002]

Don't turn off the cache no offense but it's a fruity suggestion. Also, you do want an 8MB drive cache. No, it doesn't make a difference when you're capturing but for everything else on your system (including video editing) it makes a huge difference.

I had a 2MB cache drive before now an 8MB Western Digital and I've never bothered to touch the cache. I've captured thousands of hours of video and there has been absolutely no difference between the 2GB and the 8GB drives. Also I lose maybe on average 44 frames out of a 2 hour movie which is AS LOW AS IT GETS. The only thing that will cause you to lose frames is having a CPU that is too slow to keep up with the video stream and/or a hard drive that isn't fast enough. 7200 RPM and UDMA 33+ should work just fine.

BTW - The difference between 2 and 8 cache is amazing on the functioning of the system, it makes a big difference in terms of load times and overall system performance. Get it.

[jennyandgreg]

I plan to use a dedicated drie for all programs which has an 8 meg cache. The other drives will be solely for video storage, nothing else.

[megaman]

I have two WD hard drives with 8 MB cache - so far so good, I wouldn't disable the cache anyway as much as they cost.

[SaSi]

The Cache for the disk merely relieves the disk from too much head movement when the operating system requests data. The cache always is beneficial when it's size is similar to the size of the data you require. So, if you had a 2~3Gb cache it would make a huge difference.

The best you can do for capturing is to use 2-3 disks with one of these RAID controllers that are being very common on m/b in the past few years in stripe mode. This means that the captured file will be concurrently written on 2-3 spindles rather than one. It almost doubles and triples the effective data-rate at which you can write to the disk. Reading is almost as fast. It's also a means to create a large disk. However, the individual disks must be of the same size.

Also, some of the IDE raid controllers are not as good as others. And all of these are "rubbish" compared with a descent SCSI RAID controller combined with ULTRA 160 SCSI drives. Especially when striped and mirrored. But these systems just add a 0 at the end of the price tag.

[bkimmle]

I have two WD harddrives with 8Mg Cache. A 80Gig and a 180Gig with a Athlon 2400+ and I have never seen a dropped frame in any of the capturing I have done.