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Please pardon me if this topic has been discussed before, but as far
as I know about the Flash memory, they have a relatively low limit on
re-write, as compared to hard disk

In situation where database use in concern, read and write operation
takes place very often

I know that there are pros and cons in this issue, but basically my
question is this --- How reliable is SSD?

Scraggy wrote:
> Penang wrote:
>> Please pardon me if this topic has been discussed before, but as far
>> as I know about the Flash memory, they have a relatively low limit on
>> re-write, as compared to hard disk
>>
>> In situation where database use in concern, read and write operation
>> takes place very often
>>
>> I know that there are pros and cons in this issue, but basically my
>> question is this --- How reliable is SSD?
>
>
> How long is a piece of string?
>
Given the quality of most netbooks, who gives a rats arse about the
drive? (with all due respect)

As with all things PC related, TAKE REGULAR BACKUPS

On 12 Aug, 07:30, Penang <kalamb...@gmail.com> wrote:
> Please pardon me if this topic has been discussed before, but as far
> as I know about the Flash memory, they have a relatively low limit on
> re-write, as compared to hard disk
>
> In situation where database use in concern, read and write operation
> takes place very often
>
> I know that there are pros and cons in this issue, but basically my
> question is this --- How reliable is SSD?

This is a maturing market and it seems that answers must vary
depending on what technologies are used in a specific device. For a
couple of pointers see

http://serverfault.com/questions/141...-of-ssd-drives

http://news.cnet.com/8301-13924_3-9896566-64.html

Note Samsung's comment in particular in the second link. Of course
manufacturers will try to allay fears.

Why not try one or try a couple of them in raid-1 form - and, of
course, take regular backups? I've seem a number of hard disks fail so
don't expect perfection from either technology.

James

On Tue, 11 Aug 2009 23:30:35 -0700 (PDT), Penang
<> wrote:

>Please pardon me if this topic has been discussed before, but as far
>as I know about the Flash memory, they have a relatively low limit on
>re-write, as compared to hard disk
>
>In situation where database use in concern, read and write operation
>takes place very often
>
>I know that there are pros and cons in this issue, but basically my
>question is this --- How reliable is SSD?

If you want to find a useful answer, you will need to dig much
deeper into this matter.

What harddisk? A US$ 50 2.5" laptop harddisk ? or a US$ 1000
15.000 rpm SAS server drive ?

What SSD ? NAND Flash, NOR Flash, single cell, multi level cell ?

As a rule of thumb: Flash doesn't just replace magnetics.
To justify the use of flash memory, you will need at least one
other reason.
And --very important, imho-- a file and operating system that is
tuned to flash, while all current mainstream OSs are disk-tuned
only

--
Kind regards,
Gerard Bok

darklight <> pinched out a steaming pile
of<>:

>Question how many times do you read write to a hard drive in a year?
>Question how many times do you think you will read write to a ssd in a
year?
>
>Then go and buy a usb stick and read write to it then come back and
tell us
>how long it took you break it. And how many read write operations it
took
>to break it.
>
>I assume we will hear from you in a couple of years.
>
What about swapfiles, mate?

^_^


--
http://www.youtube.com/watch?v=COaoYqkpkUA
cageprisoners.com|www.snuhwolf.9f.com|www.eyeonpalin.org
_____ ____ ____ __ /\_/\ __ _ ______ _____
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_\ \/ / /_/ / _ / \ / \ \| \| \ \_\ \ \__\ _\
/___/_/|_/\____/_//_/ \_@_/ \__|\__|\____/\____\_\

Penang wrote:
> Please pardon me if this topic has been discussed before, but as far
> as I know about the Flash memory, they have a relatively low limit on
> re-write, as compared to hard disk
>
> In situation where database use in concern, read and write operation
> takes place very often
>
> I know that there are pros and cons in this issue, but basically my
> question is this --- How reliable is SSD?

http://www.imation.com/PageFiles/83/...hite-Paper.pdf

The last page of the report addresses "wearout" as a function of writes.
As far as I can tell, they use the best kinds of writes (large sequential),
to make the estimate.

The flash block size is 128KB. If you want to update 4KB of that,
you have to rewrite the whole thing. So relatively speaking, it is
"32x" more expensive, to deal with the small sized write.

To understand whether SSD may be of value to you, you need to know
how much data you write per day. If it is a small amount, then it may
not matter what size the writes are. If you write large amounts of
data, then you'd want to understand the characteristics very well.
(That means sorting all the writes into "size bins".)

Before you buy anything, you should also read some recent reviews
of SSD products, and some of the performance problems they can have.
Don't just buy the SSD with the lowest price. You're regret it.
This is a hint as to what you're looking for. There are more articles
around, which test for this.

http://www.anandtech.com/cpuchipsets...spx?i=3403&p=8

If you want to build a test system for evaluation, use Intel
X25-E SSDs.

*******

None of the above addresses "reliability" as such. The above addresses
"wearout", where you know the thing will eventually fail, as a function
of how many writes you've done. Wear leveling makes the most of the
write cycle limits of SLC or MLC flash chips.

Reliability takes into account other things, like how often a
flash chip just rolls over and dies for no particularly good reason.
Take the stick of RAM in my previous computer as an example - one entire
chip stopped responding, after about two years of usage. Why did that happen ?
That is an example of something not accounted for as wearout -
that is a device failure unrelated to usage. RAM should not
wear out. And yet I've had failures at the two year mark (the
stick was not abused, and the computer case is cooled well).
If the chips in a flash drive do that too, then not only would
I have wearout to consider, I'd have device reliability
(chips dying) to add to the effect. And the only way to study that
in any effective way, is to get field return data for SSD drives.
And nobody gives out field return data.

Paul

On Aug 12, 2:41*pm, Paul <nos...@needed.com> wrote:
> Penang wrote:
> > Please pardon me if this topic has been discussed before, but as far
> > as I know about the Flash memory, they have a relatively low limit on
> > re-write, as compared to hard disk
>
> > In situation where database use in concern, read and write operation
> > takes place very often
>
> > I know that there are pros and cons in this issue, but basically my
> > question is this --- How reliable is SSD?
>
> http://www.imation.com/PageFiles/83/...etime-White-Pa...
>
> The last page of the report addresses "wearout" as a function of writes.
> As far as I can tell, they use the best kinds of writes (large sequential),
> to make the estimate.
>
> The flash block size is 128KB. If you want to update 4KB of that,
> you have to rewrite the whole thing. So relatively speaking, it is
> "32x" more expensive, to deal with the small sized write.
>
> To understand whether SSD may be of value to you, you need to know
> how much data you write per day. If it is a small amount, then it may
> not matter what size the writes are. If you write large amounts of
> data, then you'd want to understand the characteristics very well.
> (That means sorting all the writes into "size bins".)
>
> Before you buy anything, you should also read some recent reviews
> of SSD products, and some of the performance problems they can have.
> Don't just buy the SSD with the lowest price. You're regret it.
> This is a hint as to what you're looking for. There are more articles
> around, which test for this.
>
> http://www.anandtech.com/cpuchipsets...spx?i=3403&p=8
>
> If you want to build a test system for evaluation, use Intel
> X25-E SSDs.


One funny thing is --- Intel has just announced the suspension of
their X25-E SSD product

Reason? Technical

But rumors of pre-mature deaths of the SSD may cause Intel to think
twice about selling products that don't work


>
> *******
>
> None of the above addresses "reliability" as such. The above addresses
> "wearout", where you know the thing will eventually fail, as a function
> of how many writes you've done. Wear leveling makes the most of the
> write cycle limits of SLC or MLC flash chips.
>
> Reliability takes into account other things, like how often a
> flash chip just rolls over and dies for no particularly good reason.
> Take the stick of RAM in my previous computer as an example - one entire
> chip stopped responding, after about two years of usage. Why did that happen ?
> That is an example of something not accounted for as wearout -
> that is a device failure unrelated to usage. RAM should not
> wear out. And yet I've had failures at the two year mark (the
> stick was not abused, and the computer case is cooled well).
> If the chips in a flash drive do that too, then not only would
> I have wearout to consider, I'd have device reliability
> (chips dying) to add to the effect. And the only way to study that
> in any effective way, is to get field return data for SSD drives.
> And nobody gives out field return data.
>
> * * Paul

Penang schrieb:
> Please pardon me if this topic has been discussed before, but as far
> as I know about the Flash memory, they have a relatively low limit on
> re-write, as compared to hard disk
>
> In situation where database use in concern, read and write operation
> takes place very often
>
> I know that there are pros and cons in this issue, but basically my
> question is this --- How reliable is SSD?

Hi Penang,

sorry for joining in so late, but I did not have access to
usenet the last 4 days.

You will find a l o t of useful information at
www.storagesearch.com

To make it short:
A flash disk is not a real SSD.
Real SSDs do like 16K IOPS per disk
and they are very reliable, very expensive and
on the market for like 20+ years.

There are 2 types of flash disks: SLC (single layer) -
smaller (i.e.upto 64GB), more expensive and faster.
MLC (multi layer) - those are bigger (upto 512GB from
Toshiba) usually 256 GB now and in the EUR 600 price
range for 256 GB.

So if a flash disk 'wears out' first thing to happen is,
that is gets slower, much slower, that is, and in a
short period of time (exactly this is Intel's problem atm).

After a long period they finally are so slow, that I think
they might never die from wearing out .....
I am not that far in testing, though.

What I do in week 9 atm is trying to do harm to the
ones I testing. I give them 2800 IOPS writing only
and 2 KB blocks only. I have to types: internally
having 4 KB blocks or 8 KB blocks.
So I write 86400 x 2800 blocks per day for 64 days now.
None is slower that at the beginning - so far.

If you can throw in a lot of money, have a look
at the real speed: Texas Memory Systems
www.ramsan.com

Or on a much cheaper scale: the 12 slot boxes from
www.infortrend.com (in heavy use at CERN, Switzerland).

And n e v e r e v e r go RAID5 using a flash disk!
Writing the parity there kills a third of the lifetime.
www.baarf.com has all on RAID5 and why never it is a good
idea.

dic_k

--
Richard Kofler
SOLID STATE EDV
Dienstleistungen GmbH
Vienna/Austria/Europe

Penang wrote:
>
> One funny thing is --- Intel has just announced the suspension of
> their X25-E SSD product
>
> Reason? Technical
>
> But rumors of pre-mature deaths of the SSD may cause Intel to think
> twice about selling products that don't work
>

Link ?

Paul

Paul schrieb:
> Penang wrote:
>>
>> One funny thing is --- Intel has just announced the suspension of
>> their X25-E SSD product
>>
>> Reason? Technical
>>
>> But rumors of pre-mature deaths of the SSD may cause Intel to think
>> twice about selling products that don't work
>>
>
> Link ?
>
> Paul
>
Hi Paul

here is one of the many links:
http://www.digitimes.com/bits_chips/a20090731PD216.html

Further infos and bg infos is here
http://storagesearch.com/

search for
'Why Consumers Can Expect More Flaky Flash SSDs'

dic_k
--
Richard Kofler
SOLID STATE EDV
Dienstleistungen GmbH
Vienna/Austria/Europe