Tivo without HDD - solid state storage

TivoTown · 10-30-2007, 11:00 AM

I see in the news that we maybe only 2 years away from 1TB USB thumb drives! I wonder if anyone has tried a Tivo with solid state storage yet? I did a search but couldn't find an obvious reference.

I guess the current way would be to use a memory card IDE adapter or buy one of the expensive solid state 2.5" drives....

tenwiseman · 10-30-2007, 12:13 PM

Can't see any benefit of trying this with the current (and only UK) TiVo hardware.

ColinYounger · 10-30-2007, 12:14 PM

Solid state has been discussed before on here - the general opinion was that it probably wouldn't be very good for PVR (i.e. TiVo) usage as the 'disk' is constantly writing (for the live buffer) and might be on the sluggish side.

I very much doubt a 1Tb thumb would be very fast when it comes out - I have an fast SanDisk 4Gb here and it's still noticeably slower than a real hard drive. Even on a laptop (which historically have slower HDs)!

What I'd like to see is use of USB drive caddies on a TiVo.

Ian_m · 10-31-2007, 04:21 AM

Quote:

Originally Posted by ColinYounger

I very much doubt a 1Tb thumb would be very fast when it comes out - I have an fast SanDisk 4Gb here and it's still noticeably slower than a real hard drive. Even on a laptop (which historically have slower HDs)!

I have some systems with x133 8GB Compact FLASH in running XP embedded and they are very much slower than running straight from hard disks. I think it gets 18MB/sec read and about half to a quarter to that on write compared to 100MB/sec read/write with IDE.

TCM2007 · 10-31-2007, 04:50 AM

The advantage would be quietness, heat and size, not speed.

mikerr · 10-31-2007, 04:53 AM

Quote:

Originally Posted by Ian_m

I have some systems with x133 8GB Compact FLASH in running XP embedded and they are very much slower than running straight from hard disks. I think it gets 18MB/sec read and about half to a quarter to that on write compared to 100MB/sec read/write with IDE.

Now try seek times, and anything that would make the disk head thrash

Hard disks get very slow as soon as you move away from sustained read/write

blindlemon · 10-31-2007, 05:02 AM

Well, if anybody has £270 to splash out on an experiment, I'd be happy to configure this for TiVo use

Not exactly value for money compared to Samsung's traditional hard drives, but could be an interesting experiment....

terryeden · 10-31-2007, 05:57 AM

What would be of more interest to me would be diverting recording from an internal HDD to a NAS.

Take a, say, 4GB Compact Flash card and IDE adaptor for the TiVo's OS (and TiVoWeb etc) and redirect all recording to the cachecard. To reduce network saturation, it might be worth dropping the Live TV buffer to low quality - or stopping it.

Is there a version of CIFS or Samba compiled for TiVo?

TCM2007 · 10-31-2007, 06:31 AM

Even with a Cachecard getting "live" streaming TO a TiVo can be touch and go. No problem with the sending speed, receiving is the limiting factor. It can be done, but quite a lot of tweaking is needed.

Mike B · 10-31-2007, 12:15 PM

The prohibitive thing (aside from the price) would be that flash device can only sustain a certain amount of writes before they begin to degrade. In an application such as TiVo, the flash wouldn't last very long at all, and would almost certainly be outlived by any hard disk (even a Maxtor

).

According to a popular internet wiki-based encyclopedia:

Quote:

"Flash memory, regardless of format, supports only a limited number of erase/write cycles before a particular "sector" can no longer be written. Memory specifications generally allow 10,000[1] to 1,000,000 write cycles."

TCM2007 · 10-31-2007, 12:57 PM

A million write cycles is quite a few in a TiVo context - a cycle is only done when a recording is erased to be replaced by a new one. It would be about 4,000 years before my daily recording of Newsnight caused its bit of the "disk" to fail. You'd have the live buffer in volatile RAM.

Mike B · 10-31-2007, 01:05 PM

Quote:

Originally Posted by TCM2007

A million write cycles is quite a few in a TiVo context - a cycle is only done when a recording is erased to be replaced by a new one. It would be about 4,000 years before my daily recording of Newsnight caused its bit of the "disk" to fail. You'd have the live buffer in volatile RAM.

You'd be surprised - I've had flash that has only been written to a few tens of times a day fail inside a year.

TCM2007 · 10-31-2007, 06:28 PM

Any given sector of a TiVo disk won't get rewitten more often than once a week or so I would guess, probably much less often, 70-fold less the flash drive that you've had issues with. So say 50 years worth - should be OK!

blindlemon · 10-31-2007, 06:35 PM

Quote:

Originally Posted by TCM2007

Any given sector of a TiVo disk won't get rewitten more often than once a week or so I would guess, probably much less often

For the data areas on a large drive that may be true, but the database and logfiles are being updated all the time.

TCM2007 · 11-01-2007, 05:27 AM

They can be held in volatile ram, cf cachecard, if you were designing such a system from scratch.

blindlemon · 11-01-2007, 05:36 AM

But in that case what happens when you get a power outage? Database corruption.

The cachecard holds a copy of the database in its RAM (if fitted) to speed up reads, but it's a write-through cache so all writes also go immediately to the drive.

terryeden · 11-01-2007, 05:49 AM

That's why the disks (not the OS) use wear-levelling. It makes sure that all areas of the disk get equal wear and tear. In solid-state-storage there is no such thing as a physical area which gets more attention than another.

At least, that's the theory!