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Discussion in 'TiVo Coffee House - TiVo Discussion' started by xemand, Apr 26, 2012.
Has anyone tried to use one of the new Solid State Hard Drives in a Tivo?
Most SSD driives are 2.5" SATA drives, the drives in TiVo are 3.5" SATA drives. It wouldn't work out, plus most SSD drives at a good price are $1/GB, not good pricing if you wanted to store lots of recordings.
It should theoretically work fine, except there is no way to know whether the OS will recognize the need to enable TRIM. Without this, the drive would suffer from corruption in time. As the drive would constantly be written to, this would probably happen sooner than you might think.
Don't see the point of using a SSD for a Tivo when a standard hard drive has at least enough speed to keep up with 4 shows being recorded at the same time while also playing a show and streaming a show. And of course SSDs have low storage capacites and much higher per GB costs.
Now the design of a Tivo might benefit from a small SSD to house the OS and guide data and show directory etc. But it wouldn't have to be more than a few GBs. And it would be something Tivo would have to build into the device.
They make combination drives that combine an SSD with a conventional hard drive, with that SSD being used by the drive as a fast cache. It would be good if you could get custom software to permanently map the SSD to a known block range and put your OS partition there.
If you search this community you will find that there are a couple of threads on this topic.
I'll help. AFAIK, this guy was the first to try it.
I know someone mentioned other threads.. but as far as this part, I don't think it's true.. I think people can manually set up partitions so that the OS would be on the SSD, and the show partition(s) would be on a hard drive.
I wonder how much this would speed up the glacially slow rebooting of a TivoHD.
You would be separating the MFS partitions from the others. I haven't seen a place to indicate /dev/hdx = something different but I'm sure it's possible.
Don't SSD's have terrible wear and life with multiple re-writes, and is that not EXACTLY what a DVR does a lot: Record (Write)->Erase (not really, but you know what I mean)->Record over again (Rewrite). I think, in the long run, one is better off with an HDD. SDD's have much better life as a boot disk.
The OS partition is quite small and only really read at start-up. Putting it on a SSD Hybrid HD would be pointless, imo. The startup procedure is painfully slow for other reasons. If the entire drive was SSD, it may help, but as others have pointed out, the rewrite cycles would undoubtedly shorten the life of the drive. Even advanced drives that do their own TRIM-type algorithms to reduce wear would most likely degrade much more quickly than in a normal PC. Spend a lot of money, save some power/heat, minimal to no noticeable speed improvement, and have to replace the drive more often. Doesn't seem like a win to me.
incorrect, TRIM is just a performance optimization.
The thing with SSDs is that they need to be erased before writing, and the erase size is much bigger than the sector size. When an SSD gets a request to write a sector, the sector in the SSD array is marked as "dirty" and the new sector written in a new area (as part of wear-levelling).
Now, when all the empty blocks are gone, the SSD has to erase one. It does this by moving the non-dirty sectors to a new block so the data is still preserved. Dirty sectors are not moved because a clean version exists elsewhere in the array. Then the block is erased and ready for use again.
Now, let's say a sector contains data that the OS doesn't care about anymore (i.e., deleted file). If the OS never writes to that sector, the SSD will still dutifully copy the sector to a new flash block even though the OS will not request it (the SSD doesn't know any better). What TRIM does is form a way for the OS to tell the SSD that the sector is no longer needed. That way, when the file is deleted, the OS then TRIMs the sectors so the SSD will simply not move the contents of those sectors to a new block when it comes time to erase. This obviously speeds up operations as the SSD is not moving sectors around that the OS will never request. (If the OS does request it, it returns all zeros as the SSD has marked it as TRIMmed).
So no, you won't get data corruption. Early reports of data corruption have been due to firmware bugs in the quest for more speed from an SSD. After all, the largest users of SSDs would be companies like Apple and Dell who use millions of the things a year. If there was a problem, it would hit one of these machines first (especially if it was an Apple - you'd hear about it seconds after it happened). Instead, the reports come from the enthusiast sector buying up the latest and greatest SSDs often with very beta and buggy firmware. The PC manufacturers use more conservative SSDs from manufacturers like Toshiba and Samsung (vs. enthusiast SSDs from OCZ, Corsair and other companies) running more stable firmware. As a result, you'll only get 100MB/sec write speeds and 150MB/s read speeds - slower, but less risk of data loss.
TiVo is probably a poor fit for an SSD as it's constantly writing so you get wear on the SSD (the wear comes from erase-write cycles) without much benefit. In fact, a TiVo is more suited to a SSD-HD hybrid - SSD for the main OS partitions, and HD for the media storage. Or include the MFS application partition as well to include the databases, but store all the video on the hard drive. This way doing all the normal TiVo housekeeping is fast, and the hard drive is there for mass storage (video is perfect for hard drives - not much seeking at all).
Maybe in the mean time one of those hybrid HD's from seagate might work. I've seen near-SSD like performance with those.
Not really. The TiVo implements a read-mostly OS, with nothing but a few log files being written. The aggregate load time for the entire OS is less than 10 seconds. There are hard drives available that have an SSD built in, and a few users have installed them in TiVos. These drives boast blazing speeds, but they offer almost no advantage in the TiVo.
Surely. 'Not difficult, at all.
Not even a tiny bit. The hard drive is not the bottleneck.
No, not that, either.
This will help a small, but noticeable amount with the menus, but not a reasonable amount given the cost.
They work, but the performance increase is only marginal.
Yes, but not in a TiVo.
I stand corrected. My SSD experience is largely in the Sun ZFS LogZilla/ReadZilla space. The Sun engineers explained to me how they had implemented TRIM to avoid data corruption, but they were not specific about how it worked.
It would be of no benefit on a TiVo. The read speed of the hard drive is not really ever a factor on a TiVo. Reading a video file faster wouldn't make it play faster. Maybe you get a few seconds improvement in startup time when the OS partition is read but other than that, you get no benefit. Plus, the drive will certainly die a much quicker death as it would be written to 24/7 and this is not something SSD drives excel at.
Then what is the bottleneck for boot time on a TiVo?
I know, you *shouldn't* need to reboot them, but things like power outages (yes, get a UPS), OS bugs (yes, one is due to me not re-pairing my cablecards), and heck, the OS eventually corrupting which happened to one of my drives, caused reboots..
Is there a hack to make the reboot a lot faster? Heck, I wouldn't even mind if the time to RECORDING again still took ~10 minutes... but just being able to get back to now playing faster than ~5-6 minutes would be useful.
What do you believe the bottleneck is in a Tivo boot cycle?
Assuming it's due to running cryptographic hashes to verify the filesystem is unmodified, is that CPU-bound instead of disk-bound?
The TiVo has to execute a ton of real-time processes during boot. The code (which is relatively tiny) loads in almost no time at all, but the system has to wait for each device to return a ready status.
Note the TiVo is not really all that slow at booting, especially when you consider the S3 only has a 300MHz single core processor. A Windows machine running 2+ GHz with 2 or more cores takes roughly the same amount of time to actually boot. Try putting a capture card like a Ceton in your workstation and a video file to be played in the startup folder of a Windows machine, and you will find it is about 4 - 5 minutes before the video starts playing and the capture card starts recording.