[mythtv-users] Building a new MythTV Backend for 2022

[James Linder]

> On 10 Jan 2022, at 4:46 pm, Stephen Worthington <stephen_agent at jsw.gen.nz> wrote:
> 
> On Mon, 10 Jan 2022 07:31:26 +0800, you wrote:
> 
>> Jim myth here:
>> SSD life is now so bad per cell (1000 or 10000 writes) ssd manufactures quote life in TBW.
>> The TBW spec depends directly on ssd size.
>> After 1/2 a year in use the projected life of my m2 is 40 years (regrettably more than mine :-)
>> 
>> Model Number:                       Samsung SSD 970 EVO Plus 2TB
>> Power On Hours:                     3,741
>> Data Units Written:                 29,494,374 [15.1 TB]
>> 
>> This is a cheap m2 (4 cell) at 600 TBW, you can get more expensive 1200 even 2400 TBW ssds.
>> 
>> James
> 
> Another real life example:
> 
> Model Number:                       Samsung SSD 950 PRO 256GB
> Namespace 1 Size/Capacity:          256,060,514,304 [256 GB]
> Namespace 1 Utilization:            95,130,853,376 [95.1 GB]
> Namespace 1 Formatted LBA Size:     512
> 
> SMART/Health Information (NVMe Log 0x02)
> Critical Warning:                   0x00
> Temperature:                        45 Celsius
> Available Spare:                    100%
> Available Spare Threshold:          10%
> Percentage Used:                    9%
> Data Units Read:                    360,516,312 [184 TB]
> Data Units Written:                 228,579,4 h42 [117 TB]
> Host Read Commands:                 5,169,492,455
> Host Write Commands:                2,354,847,145
> Controller Busy Time:               11,596
> Power Cycles:                       282
> Power On Hours:                     48,823
> Unsafe Shutdowns:                   133
> Media and Data Integrity Errors:    0
> Error Information Log Entries:      3,246
> 
> This is my main MythTV box - 5.5 years of 24/7 use on the SSD, and it
> is showing 9% of lifetime writes used.  It is an older SSD and the Pro
> model that has better lifetime, but it gets a lot of database
> activity.  I am pretty happy that it will last for quite a long while
> yet.
> 
> If you want to record to the SSD, then you are likely to hit the
> lifetime write limit fairly rapidly.  But just running MythTV and
> normal Linux on an SSD and there are no problems with lifetime.  You
> still need to worry about it just dying unexpectedly, like any disk
> drive (or any electronics, for that matter).

I presume smartctl is giving you 10% but it is wrong!

https://www.samsung.com/au/memory-storage/nvme-ssd/950-pro-nvme-m-2-ssd-256gb-mz-v5p256bw/

200TBW of which you used 117G so 60% life used!

In 5 years buy a bigger m2 !!

Also DO NOT put the os on the storage disks. Recovery is easy unless tou can’t write to your system disk Then you need another system disk.

James

PS most ssd’s exceeded their TBH in some cases by 2x although some cases by 0.8 or 0.9 (ie shorter) mostly samsung far exceeded their spec.