Post by PaulPost by Jeff GainesI have a QNAP NAS with 4x 2 TB SSD in RAID 6
If you're concerned with speed, then RAID6 seems an odd choice, it gives the same usable capacity as RAID10, it's slower at reading and slower at writing, it will burn up your SSD write endurance sooner ...
Yes RAID6 can survive *any* two SSDs failing, where RAID10 can survive any one SSD failing or *some* combinations of two SSDs failing, but as we all know, RAID is not a ...
Its all bollocks anyway because SSDs fail when cells die, not at some arbitrary number of writes.
This is (unfortunately) not true.
The bricking policy is unrelated to SMART, in the sense
that Intel devices do not brick because the device state
is "poor".
They brick when exactly 600TBW has expired. No more or no less.
Once the average location receives 600 writes (or whatever the
technology indicates is the number of writes), the drive
just bricks. It does not even go read-only. It just... stops working.
No any ones I have heard of
Post by PaulThis is why, as a consumer, you have to study which companies
have which policy.
Intel Device totally stops responding, after each cell written 600 times.
xxxxx Some companies, their drive goes read-only after 600 writes per cell.
This allows a final backup to be made, before retiring the device.
yyyyy And a few SSDs have no policy at all. You can use them until the
critical data corrupts (loss of map), or, there is some calamity
related to spared out blocks.
Some of these policies were tested a long time ago, in a
test series that bashed some drives continuously. And
one of the drives (one without an end of life policy), it
lasted about twice as long as predicted, and it corrupted
while in service.
I do not believe anyone has that policy today, and 600 writes is
impossibly small
E.g. Kingston quote lifetime not in writes, but in hours with an MTBF
which simply does not suggest an exact cut off....
"Nevertheless: The flash cells, which electronically store data onto an
SSD device, have a clearly defined life span, in contrast to traditional
magnetic storage devices. After a limited number of write-erase cycles,
this becomes critical, since the flash memory of an SSD ages with every
write process. Manufacturers usually state 1,000 to 100,000
write-and-erase operations.
The considerable range in the lifetime of an SSD is related to different
storage technologies:
- Single-level cell SSDs (SLC) have a particularly long life,
although they can only store 1 bit per memory cell. They can withstand
up to 100,000 write cycles per cell and are particularly fast, durable,
and fail-safe.
- Multi-level cell SSDs (MLC) have a higher storage density and can
store 2 bits per flash cell. They are more cost-effective than the SLC
type but can only tolerate up to 10,000 write cycles per cell.
- Triple-level cell SSDs (TLC) can hold 3 information bits per memory
cell. However, at the same time, life expectancy can drop to 3,000
memory cycles per cell.
- Quad-level cell SSDs (QLC) accommodate 4 information bits per
cell. Reduced costs, more storage capacity, and higher storage density
are also associated with a shorter service life with this type of
device. Manufacturers usually only guarantee 1,000 write or erase cycles
per cell.
Although the range in SSD life spans is considerable, all SSD types have
a sufficiently high life expectancy with moderate use (with some
limitations, including for QLC SSDs)."
https://www.ionos.co.uk/digitalguide/server/security/ssd-life-span/
So no absolute sudden bricking, just data degradation, followed by
remapping of 'bad blocks' and finally drive failure.
And if you don't get greedy on storage space, up to 100,000 write
operations. Or more.
IBM may have had some policy once, but it is in no way representative of
drives on sale today.
If the drive is big and the data write rate slow, as is typical in a
domestic NAS, the things should do 10+ years.
Which is better than most hard drives.
I have a friend who used to burn those out in under a year. 24x7 massive
data files being written and read.
Doing some kind of numerical analysis
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This makes me unfit for the company of people of a Left persuasion, and
all women"