Solid State Drives vs Hard Disk Drives

[nmset]

Would anyone recommend SSD for intensively used database backends, given the temporary life expectancy of the memory cells, even with buit-in wear-levelling algorithms ? Number of years to be used before maintainance change ?

[r31griffo]

Would anyone recommend SSD for intensively used database backends, given the temporary life expectancy of the memory cells, even with buit-in wear-levelling algorithms ? Number of years to be used before maintainance change ?

SSD drives have very minimal seek times...I'd definately recommend them if speed is essential.

The question you've asked is very subjective. Without knowing a little more, no one could answer with any degree of certainty...
the frequency it is being written to
which manufacturer and model of SSD (to know the guaranteed writes per bit)

besides, these are the numbers the manufactures give, are they being cautious or over estimating?

Depending on the RAID setup, you may have a performance hit in writing...I'm not sure if this will negate the benefits of SSD.

I personally would use a mechanical disk for this (because the wife doesn't let me spend much money)...If I was loaded, SSD for EVERYTHING!

[yoav_by]

Would anyone recommend SSD for intensively used database backends, given the temporary life expectancy of the memory cells, even with buit-in wear-levelling algorithms ? Number of years to be used before maintainance change ?

SSD Myths and Legends - "write endurance" article in STORAGE search .com

[nmset]

Thank you for the replies and links.
I'm looking for more info I could not find after a quick web search.

1. What does a physical memory block contain ? A bit, a byte, a number of bytes... ?

2. What happens when max-N write is commited? The data written on one block at max-N will most probably form part of a bigger dataset. Would the other blocks holding the whole dataset become logically unwritable because of one single block having reached end-of-life ? Would the whole dataset be lost ?

3. If the SSD is left on the shelf for ... 50 years... (!), would the data on it be lost, as it may happen with floppy disk ? I don't think so but I wish some confirmation.

4. If we were to use a same SSD for ... 10 years... (!), would we see a progressive decrease in disk capacity with time ? 100GB -> 98 -> 92...

5. Does max-N+1 write, if conceivable, mean the block gets blanked or destroyed ?

TIA

[oz]

Those are some good questions, nmset. Hopefully, someone that's more up to speed on SSDs and their usage than I am will jump in here with some answers, or some links to where the answers can be found.

As for comparing the two types of devices, I've been having a hard time deciding which one to stick with for the immediate future. Common sense says that SSDs will be the default storage method at some point in the future, but I'm thinking that HDDs will continue to be with us for a while.

Both have advantages and disadvantages, but another thing that I've noticed about SSDs is that they begin to lose some of their speed after using them for a while. The only thing I've found that gets that lost speed back is a full disk secure erase, then reinstalling the system to the drive. Of course, the manufacturers say that each secure erase takes a little of the life out of the drive, so routine secure erases are discouraged.

I'm anxious for the time to arrive when an SSD can be installed and used just like you would any HDD, without having to worry about disk writes and all the recommended special tweaks. Prices and storage sizes that are more in line with each other would be nice, too.

[yoav_by]

Those are some good questions, nmset. Hopefully, someone that's more up to speed on SSDs and their usage than I am will jump in here with some answers, or some links to where the answers can be found.

As for comparing the two types of devices, I've been having a hard time deciding which one to stick with for the immediate future. Common sense says that SSDs will be the default storage method at some point in the future, but I'm thinking that HDDs will continue to be with us for a while.

Both have advantages and disadvantages, but another thing that I've noticed about SSDs is that they begin to lose some of their speed after using them for a while. The only thing I've found that gets that lost speed back is a full disk secure erase, then reinstalling the system to the drive. Of course, the manufacturers say that each secure erase takes a little of the life out of the drive, so routine secure erases are discouraged.

I'm anxious for the time to arrive when an SSD can be installed and used just like you would any HDD, without having to worry about disk writes and all the recommended special tweaks. Prices and storage sizes that are more in line with each other would be nice, too.

The phenomena of speed degradation in SSD doesn't happen if TRIM command is enabled. In this case secured erase isn't needed. Besides, even if secured erase is performed, its impact on newer SSDs lifespan is negligible.

[oz]

The phenomena of speed degradation in SSD doesn't happen if TRIM command is enabled. In this case secured erase isn't needed. Besides, even if secured erase is performed, its impact on newer SSDs lifespan is negligible.

Unfortunately, that hasn't been the case on either of my OCZ Vertex 2 devices with TRIM enabled and working. I measure their speeds every other week or so just to see how they are doing, and both are slowing down although it is a very slight degradation with each benchmark. I generally try to keep up with what's happening with their SSDs and firmware over at the OCZ SSD Forums and several of their techs have advised not to do too many secure erases and/or benchmarks on them, so I'm try to keep those to a minimum while also finding out what's happening with measured speeds.

Overall, I'm pretty hard on HDDs and SSDs, constantly removing and installing different distros or system images on them, so if anyone is going to have any failures, it will probably be me. If that happens, it'll be time to see how well they stand behind their warranties.

[r31griffo]

Unfortunately, that hasn't been the case on either of my OCZ Vertex 2 devices with TRIM enabled and working. I measure their speeds every other week or so just to see how they are doing, and both are slowing down although it is a very slight degradation with each benchmark.

Do you still have the benchmark results so we can see the rate of degradation? Also, is the performance hit in writing or reading...or both?

[oz]

Do you still have the benchmark results so we can see the rate of degradation? Also, is the performance hit in writing or reading...or both?

No, I don't have the benchmarks any longer and they were read only speeds, as I've never measured write speeds on them. The degradation was happening fairly slowly, and mostly related to minimum read speeds and average read speeds. The maximum read speeds go down too, but even slower. Here's a pretty good thread where one of the staff members at the OCZ Forums discusses TRIM and speed issues on their Sandforce controller models with forum members:

General Discussion Secure Erase, TRIM, and anything else Sandforce

In my case, it might be that TRIM never gets to work as completely as it should and as intended because of the frequent removal and addition of large amounts of data to the drives. As indicated earlier, a secure erase puts everything back to the speeds they had when they were first installed.

All that said, I'm not complaining about the drives at all. They definitely feel faster, and are faster than HDDs, and I like the almost noise free environment that they provide. I say "almost" because they do make a slight squealing sound at times. Not sure what causes that. The only real drawback to them that I see is the big price for the small storage size, but seeing as how Linux users generally don't require all the space that Windows users do, they work out pretty well. Oh, and the special tweaks that are often recommended to prevent some of the disk writes can be cumbersome if you do them all and you do fresh installs very often.

It's my understanding that Intel is supposed to be coming out with some new models within the next few months, so I'm looking forward to seeing what improvements they've made. If memory serves, they are going to be using Sandforce controllers on some of them, and they are reported to be faster than current models.