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Re: Contemplating SSD Hardware RAID

From: Yeb Havinga <yebhavinga(at)gmail(dot)com>
To: Greg Smith <greg(at)2ndQuadrant(dot)com>
Cc: Florian Weimer <fweimer(at)bfk(dot)de>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Contemplating SSD Hardware RAID
Date: 2011-06-21 20:10:35
Message-ID: 4E00FABB.6030302@gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On 2011-06-21 17:11, Greg Smith wrote:
> On 06/21/2011 07:19 AM, Florian Weimer wrote:
>> 3ware controllers offer SMART pass-through, and smartctl supports it.
>> I'm sure there's something similar for Areca controllers.
>
> Depends on the model, drives, and how you access the management 
> interface.  For both manufacturers actually.  Check out 
> http://notemagnet.blogspot.com/2008/08/linux-disk-failures-areca-is-not-so.html 
> for example.  There I talk about problems with a specific Areca 
> controller, as well as noting in a comment at the end that there are 
> limitations with 3ware supporting not supporting SMART reports against 
> SAS drives.
>
> Part of the whole evaluation chain for new server hardware, especially 
> for SSD, needs to be a look at what SMART data you can get.  Yeb, I'd 
> be curious to get more details about what you've been seeing here if 
> you can share it.  You have more different models around than I have 
> access to, especially the OCZ ones which I can't get my clients to 
> consider still.  (Their concerns about compatibility and support from 
> a relatively small vendor are not completely unfounded)
>

This is what a windows OCZ tool explains about the different smart 
values (excuse for no mark up) for a Vertex 2 Pro.

SMART READ DATA
     Revision: 10
     Attributes List
       1: SSD Raw Read Error Rate                Normalized Rate: 120 
total ECC and RAISE errors
       5: SSD Retired Block Count                Reserve blocks 
remaining: 100%
       9: SSD Power-On Hours                     Total hours power on: 451
      12: SSD Power Cycle Count                  Count of power on/off 
cycles: 61
      13: SSD Soft Read Error Rate               Normalized Rate: 120
     100: SSD GBytes Erased                      Flash memory erases 
across the entire drive: 128 GB
     170: SSD Number of Remaining Spares         Number of reserve Flash 
memory blocks: 17417
     171: SSD Program Fail Count                 Total number of Flash 
program operation failures: 0
     172: SSD Erase Fail Count                   Total number of Flash 
erase operation failures: 0
     174: SSD Unexpected power loss count        Total number of 
unexpected power loss: 13
     177: SSD Wear Range Delta                   Delta between most-worn 
and least-worn Flash blocks: 0
     181: SSD Program Fail Count                 Total number of Flash 
program operation failures: 0
     182: SSD Erase Fail Count                   Total number of Flash 
erase operation failures: 0
     184: SSD End to End Error Detection         I/O errors detected 
during reads from flash memory: 0
     187: SSD Reported Uncorrectable Errors      Uncorrectable RAISE 
errors reported to the host for all data access: 0
     194: SSD Temperature Monitoring             Current: 26  High: 37 
Low: 0
     195: SSD ECC On-the-fly Count               Normalized Rate: 120
     196: SSD Reallocation Event Count           Total number of 
reallocated Flash blocks: 0
     198: SSD Uncorrectable Sector Count         Total number of 
uncorrectable errors when reading/writing a sector: 0
     199: SSD SATA R-Errors Error Count          Current SATA RError 
count: 0
     201: SSD Uncorrectable Soft Read Error Rate Normalized Rate: 120
     204: SSD Soft ECC Correction Rate (RAISE)   Normalized Rate: 120
     230: SSD Life Curve Status                  Current state of drive 
operation based upon the Life Curve: 100
     231: SSD Life Left                          Approximate SDD life 
Remaining: 99%
     232: SSD Available Reserved Space           Amount of Flash memory 
space in reserve (GB): 17
     235: SSD Supercap Health                    Condition of an 
external SuperCapacitor Health in mSec: 0
     241: SSD Lifetime writes from host          Number of bytes written 
to SSD: 448 GB
     242: SSD Lifetime reads from host           Number of bytes read 
from SSD: 192 GB

Same tool for a Vertex 3 (not pro)

SMART READ DATA
     Revision: 10
     Attributes List
       1: SSD Raw Read Error Rate                Normalized Rate: 120 
total ECC and RAISE errors
       5: SSD Retired Block Count                Reserve blocks 
remaining: 100%
       9: SSD Power-On Hours                     Total hours power on: 7
      12: SSD Power Cycle Count                  Count of power on/off 
cycles: 13
     171: SSD Program Fail Count                 Total number of Flash 
program operation failures: 0
     172: SSD Erase Fail Count                   Total number of Flash 
erase operation failures: 0
     174: SSD Unexpected power loss count        Total number of 
unexpected power loss: 10
     177: SSD Wear Range Delta                   Delta between most-worn 
and least-worn Flash blocks: 0
     181: SSD Program Fail Count                 Total number of Flash 
program operation failures: 0
     182: SSD Erase Fail Count                   Total number of Flash 
erase operation failures: 0
     187: SSD Reported Uncorrectable Errors      Uncorrectable RAISE 
errors reported to the host for all data access: 0
     194: SSD Temperature Monitoring             Current: 128  High: 129 
Low: 127
     195: SSD ECC On-the-fly Count               Normalized Rate: 100
     196: SSD Reallocation Event Count           Total number of 
reallocated Flash blocks: 0
     201: SSD Uncorrectable Soft Read Error Rate Normalized Rate: 100
     204: SSD Soft ECC Correction Rate (RAISE)   Normalized Rate: 100
     230: SSD Life Curve Status                  Current state of drive 
operation based upon the Life Curve: 100
     231: SSD Life Left                          Approximate SDD life 
Remaining: 100%
     241: SSD Lifetime writes from host          Number of bytes written 
to SSD: 162 GB
     242: SSD Lifetime reads from host           Number of bytes read 
from SSD: 236 GB


There's some info burried in 
http://archives.postgresql.org/pgsql-performance/2011-03/msg00350.php 
where two Vertex 2 pro's are compared; the first has been really 
hammered with pgbench, the second had a few months duty in a 
workstation. The raw value of SSD Available Reserved Space seems to be a 
good candidate to watch to go to 0, since the pgbenched-drive has 16GB 
left and the workstation disk 17GB. Would be cool to graph with e.g. 
symon (http://i.imgur.com/T4NAq.png)

-- 
Yeb Havinga
http://www.mgrid.net/
Mastering Medical Data


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