<div dir="ltr">Hello again Marius,<div><br></div><div>Looking at the SMART data, it is indeed a Sandforce drive; these have the added benefit of lessened write-cycles due to onboard LZO(or similar; its proprietary but seems like LZO to me) compression internal to the chipset firmware. </div><div><br></div><div>Thats where these 5 values come into play:</div><div><br></div><div><div>231 SSD_Life_Left 0x0013 100 100 010 Pre-fail Always - 0</div><div>233 SandForce_Internal 0x0032 000 000 000 Old_age Always - 1445</div><div>234 SandForce_Internal 0x0032 000 000 000 Old_age Always - 729</div><div>241 Lifetime_Writes_GiB 0x0032 000 000 000 Old_age Always - 729</div><div>242 Lifetime_Reads_GiB 0x0032 000 000 000 Old_age Always - 189</div></div><div><br></div><div>233 is "actual bytes over the SATA Bus written"; 234 is "bytes after compression" and it should almost always match 241 "Lifetime Writes" which is directly to the NAND. Reads is even lower.</div><div><br></div><div>231 is the Sandforce numbered metric similar to the aforementioned 233 Media_Wearout_Indicator metric. Different numbers, same basic principle. You're still at 100/100 which is still "pretty close to new" in the grand scheme of things.</div><div><br></div><div>My own 60GB Sandforce drive has way more writes/reads than yours, nearly triple for 1/2 the amount of NAND Onboard. </div><div><br></div><div><div>195 ECC_Uncorr_Error_Count 0x001c 120 120 000 Old_age Offline - 0/0</div><div>196 Reallocated_Event_Count 0x0033 100 100 000 Pre-fail Always - 0</div><div>231 SSD_Life_Left 0x0013 100 100 010 Pre-fail Always - 0</div><div>233 SandForce_Internal 0x0000 000 000 000 Old_age Offline - 3520</div><div>234 SandForce_Internal 0x0032 000 000 000 Old_age Always - 3904</div><div>241 Lifetime_Writes_GiB 0x0032 000 000 000 Old_age Always - 3904</div><div>242 Lifetime_Reads_GiB 0x0032 000 000 000 Old_age Always - 10944</div><div><br></div></div><div>As this shows, my write-load hasn't been so easily LZO compressed, and internal wear-leveling has made the 'write amplification' about 1.1 the input bytes. 3.9TiB written to the flash, over its lifecycle with only 3.5 TiB of input data. Yours shows the approximate 1/2 write reduction possible when the majority of files on the drive are textual or easily compressed. I've written a lot of already-compressed data to the disk over its lifetime, doing many Gentoo package updates and compiles, which implies a ton of bz2/xz files written over the years. </div><div><br></div><div>Both of our 'worst case scenario' disks should still last long into next decade as long as the electronics don't die first :) </div><div><br></div><div>Mike</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Nov 22, 2017 at 1:57 PM, Marius Schrecker <span dir="ltr"><<a href="mailto:marius.schrecker@lyse.net" target="_blank">marius.schrecker@lyse.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5"><br>On Wednesday, November 22, 2017 19:01 CET, Keith Pyle <<a href="mailto:kpyle@austin.rr.com" target="_blank">kpyle@austin.rr.com</a>> wrote:<br> <blockquote type="cite" cite="http://f2da626e-d5ec-73da-f917-7c86371803bc@austin.rr.com">On 11/22/17 08:17, Marius Schrecker wrote:<br>> ? I am repurposing an old, box that was previously used as a combined mythtv backend/frontend, Logitech Media Server and nfs fileserver as a mythtv backend only.<br>><br>> The system has a maximum of 8GB RAM, a quite well used 120GB SSD (no signs of failure yet) and I just replaced the 3TB media storage spindle drive with a new 4TB unit.<br>><br>> My main concern is offloading the SSD as much as possible to prolong its life.<br><br>Marius,<br><br>Mike's comments are quite correct. Look in your smartctl output for a<br>line similar to this:<br><br>ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE<br>UPDATED WHEN_FAILED RAW_VALUE<br><br>233 Media_Wearout_Indicator 0x0032 098 098 000 Old_age<br>Always - 0<br><br>Many SSD's include this metric as an indicator of how much wear leveling<br>has been done (strictly speaking, it's a NAND erase cycle metric).<br>Intel defined this metric for their SSD's, but I've seen it on non-Intel<br>drives too. A new drive should show a value of 100. A value of 1<br>means the drive has reached its designed write cycle limit, but it may<br>well continue working past that point. The value is a linear function<br>of the write/erase cycle count.<br><br>The line above is for an 80 GB Intel MLC SSD that has 72000 hours of use<br>(8 years) in my Myth backend as the OS and DB drive. It shows total<br>writes of just under 7 TB. It was at ~62000 hours of use that it<br>dropped from 99 to 98. So, for a pure backend, a decent SSD will work<br>fine for a very long time. It may well die due to other failures long<br>before reaching a write limit. For my backend workload, this drive's<br>flash should have another 300+ years. :-)<br><br>With regard to memory, Linux will happily use whatever you provide for<br>caching. The right amount of caching is highly dependent on what you<br>run. If your workload involves frequently reading the same data many<br>times, you'll benefit from having enough memory to keep that frequently<br>accessed data in cache. For a Myth backend that runs commflag jobs, it<br>can help to have the video data still in memory rather than re-reading<br>it from disk.<br><br>My backend runs Myth, mysql, and apache. It has 4 GB and typically has<br>1.0-1.5 GB in the "used" category. That leaves 2.5-3.0 GB being used<br>for cache and I don't see any signs of the system being resource stressed.<br><br>Keith<br> </blockquote></div></div>Thanks Keith,<br><br> My drive doesn't seem to display that metric, but one or two others seem to suggest that there'e plenty of life left. Here's the table again:<br><span id="m_2286034964420824118messageContent"><span class="">ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE<br></span> 1 Raw_Read_Error_Rate 0x0033 120 120 050 Pre-fail Always - 0/0<br> 5 Retired_Block_Count 0x0033 100 100 003 Pre-fail Always - 0<br> 9 Power_On_Hours_and_Msec 0x0032 084 084 000 Old_age Always - 14095h+59m+25.710s<br> 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 103<br>171 Program_Fail_Count 0x000a 000 000 000 Old_age Always - 0<br>172 Erase_Fail_Count 0x0032 000 000 000 Old_age Always - 0<br>174 Unexpect_Power_Loss_Ct 0x0030 000 000 000 Old_age Offline - 37<br>177 Wear_Range_Delta 0x0000 000 000 000 Old_age Offline - 1<br>181 Program_Fail_Count 0x000a 000 000 000 Old_age Always - 0<br>182 Erase_Fail_Count 0x0032 000 000 000 Old_age Always - 0<br>187 Reported_Uncorrect 0x0012 100 100 000 Old_age Always - 0<br>189 Airflow_Temperature_Cel 0x0000 017 043 000 Old_age Offline - 17 (Min/Max 8/43)<br>194 Temperature_Celsius 0x0022 017 043 000 Old_age Always - 17 (Min/Max 8/43)<br>195 ECC_Uncorr_Error_Count 0x001c 120 120 000 Old_age Offline - 0/0<br>196 Reallocated_Event_Count 0x0033 100 100 003 Pre-fail Always - 0<br>201 Unc_Soft_Read_Err_Rate 0x001c 120 120 000 Old_age Offline - 0/0<br>204 Soft_ECC_Correct_Rate 0x001c 120 120 000 Old_age Offline - 0/0<br>230 Life_Curve_Status 0x0013 100 100 000 Pre-fail Always - 100<br>231 SSD_Life_Left 0x0013 100 100 010 Pre-fail Always - 0<br>233 SandForce_Internal 0x0032 000 000 000 Old_age Always - 1445<br>234 SandForce_Internal 0x0032 000 000 000 Old_age Always - 729<br>241 Lifetime_Writes_GiB 0x0032 000 000 000 Old_age Always - 729<br>242 Lifetime_Reads_GiB 0x0032 000 000 000 Old_age Always - 189</span><br><br><br>BR.<span class="HOEnZb"><font color="#888888"><br><br>-Marius--<br>
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