Re: Recommendations for SSDs in production?

On 11/4/2011 8:26 AM, Yeb Havinga wrote:
>
> First, if your'e interested in doing a test like this yourself, I'm
> testing on ubuntu 11.10, but even though this is a brand new
> distribution, the smart database was a few months old.
> 'update-smart-drivedb' had as effect that the names of the values
> turned into something useful: instead of #LBA's written, it now shows
> #32MiB's written. Also there are now three 'workload' related parameters.
>
I submitted the patch for these to smartmontools a few weeks ago and it
is now in the current db but not yet in any of the distro update
packages. I probably forgot to mention in my post here that you need the
latest db for the 710. Also, if you pull the trunk source code and build
it yourself it has the ability to decode the drive stats log data
(example pasted below). I haven't yet found a use for this myself, but
it does seem to have a little more informaiton than the SMART
attributes. (Thanks to Christian Franke of the smartmontools project for
implementing this feature)

Your figures from the workload wear roughly match mine. In production we
don't expect to subject the drives to anything close to 100% of the
pgbench workload (probably around 1/10 of that on average), so the
predicted wear life of the drive is 10+ years in our estimates, under
production loads.

The big question of course is can the drive's wearout estimate be
trusted ? A little more information from Intel about how it is
calculated would help allay concerns in this area.

# ./smartctl -l devstat,0 /dev/sda
smartctl 5.42 2011-10-10 r3434 [x86_64-linux-2.6.32-71.29.1.el6.x86_64] (local build)
Copyright (C) 2002-11 by Bruce Allen,http://smartmontools.sourceforge.net

Device Statistics (GP Log 0x04) supported pages
Page Description
0 List of supported log pages
1 General Statistics
4 General Errors Statistics
5 Temperature Statistics
6 Transport Statistics
7 Solid State Device Statistics

# ./smartctl -l devstat /dev/sda
smartctl 5.42 2011-10-10 r3434 [x86_64-linux-2.6.32-71.29.1.el6.x86_64] (local build)
Copyright (C) 2002-11 by Bruce Allen,http://smartmontools.sourceforge.net

Device Statistics (GP Log 0x04)
Page Offset Flg Size Value Description
1 ===== == = = == General Statistics (rev 2) ==
1 0x008 V- 4 10 Lifetime Power-On Resets
1 0x010 V- 4 200 Power-on Hours
1 0x018 V- 6 3366822529 Logical Sectors Written
1 0x020 V- 6 248189788 Number of Write Commands
1 0x028 V- 6 54653524 Logical Sectors Read
1 0x030 V- 6 2626204 Number of Read Commands
4 ===== == = = == General Errors Statistics (rev 1) ==
4 0x008 V- 4 0 Number of Reported Uncorrectable Errors
4 0x010 V- 4 0 Resets Between Cmd Acceptance and Completion
5 ===== == = = == Temperature Statistics (rev 1) ==
5 0x008 V- 1 21 Current Temperature
5 0x010 V- 1 20 Average Short Term Temperature
5 0x018 -- 1 20 Average Long Term Temperature
5 0x020 V- 1 30 Highest Temperature
5 0x028 V- 1 17 Lowest Temperature
5 0x030 V- 1 23 Highest Average Short Term Temperature
5 0x038 V- 1 18 Lowest Average Short Term Temperature
5 0x040 -- 1 -128 Highest Average Long Term Temperature
5 0x048 -- 1 -128 Lowest Average Long Term Temperature
5 0x050 V- 4 0 Time in Over-Temperature
5 0x058 V- 1 70 Specified Maximum Operating Temperature
5 0x060 V- 4 0 Time in Under-Temperature
5 0x068 V- 1 0 Specified Minimum Operating Temperature
6 ===== == = = == Transport Statistics (rev 1) ==
6 0x008 V- 4 77 Number of hardware resets
6 0x010 V- 4 22 Number of ASR Events
6 0x018 V- 4 0 Number of Interface CRC Errors
7 ===== == = = == Solid State Device Statistics (rev 1) ==
7 0x008 V- 1 0 Percentage Used Endurance Indicator
||_ N normalized
|__ V valid