[Beowulf] SSD performance
ariel sabiguero yawelak
asabigue at fing.edu.uy
Sun Jul 22 06:52:01 PDT 2018
Cheap drives (I use Crucial, AMD Radeon and Kingston) accept 3.000
rewrites per memory block. There are a few of interesting attributes you
can check from SMART. These are from my laptop (Crucial_CT960M500SSD1)
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE
UPDATED WHEN_FAILED RAW_VALUE
9 Power_On_Hours 0x0032 100 100 000 Old_age
Always - 8611
12 Power_Cycle_Count 0x0032 100 100 000 Old_age
Always - 4800
173 Ave_Block-Erase_Count 0x0032 096 096 000 Old_age
Always - 134
180 Unused_Reserve_NAND_Blk 0x0033 000 000 000 Pre-fail
Always - 16523
202 Percent_Lifetime_Used 0x0031 096 096 000 Pre-fail
Offline - 4
206 Write_Error_Rate 0x000e 100 100 000 Old_age
Always - 0
210 Success_RAIN_Recov_Cnt 0x0032 100 100 000 Old_age
Always - 0
246 Total_Host_Sector_Write 0x0032 100 100 --- Old_age
Always - 19329755627
247 Host_Program_Page_Count 0x0032 100 100 --- Old_age
Always - 616802682
248 Bckgnd_Program_Page_Cnt 0x0032 100 100 --- Old_age
Always - 3344366909
Attribute 173 states that, on average, each block was erased 134 times,
and states that it is about 4% of the liftime of the drive (attribute
202) was used. Check those/similar values on your drive. 4% on 8.611hs
suggests that I can continue to use the drive another 23 more years.
A few things you should consider:
* There is no wear from reading
* You should have as much free space as possible in order to level the
wearing. If your filesystem is pretty much full, all the
wear-leveing will occur on those few blocks that are released and
re-used. If you only have one block left, you will kill it in 3000
writes :-)
* Your filesystem shouls be aware that it is running on SSD in order
to mark blocks as free (so the SSD can do it's magic). I finally
dropped reiserfs for this reason.
* lot more things to consider, but these are the most relevant IMHO
* YMMV
Would you like to share your counters? Filesystem? application?
regards
ariel
El 22/07/18 a las 04:02, Jonathan Engwall escribió:
> Does 345 power_on_hours seem like "old age"
> Not happy. Thanks for the CEPH tip.
>
> On Sat, Jul 21, 2018, 11:30 PM Jonathan Engwall
> <engwalljonathanthereal at gmail.com
> <mailto:engwalljonathanthereal at gmail.com>> wrote:
>
> I built up a couple r610 dells with the idea that they would boot
> from ssd through a usb external drive. The cheap external drives
> might be the real culprits. I have to think about that.
> The latest drive to fail was a Kingston and I think it was new.
> There is a write limit on some ssds?
> Lately I have been building trying to crosscompile the cray xmp
> simulator. It has thousands of targets. But earlier this week
> afterI installed openvswitch was when the trouble began.
> Jonathan Engwall
>
> On Sat, Jul 21, 2018, 10:44 PM John Hearns via Beowulf
> <beowulf at beowulf.org <mailto:beowulf at beowulf.org>> wrote:
>
> I forgot the main purpose of the Internet. My bad.
> >You don't say for which purpose the SSDs are being used.
> Storing cat pics?
>
> On 22 July 2018 at 07:41, John Hearns <hearnsj at googlemail.com
> <mailto:hearnsj at googlemail.com>> wrote:
>
> You don't say for which purpose the SSDs are being used.
> In your laptop?
> As system disks in HPC compute nodes?
> Journalling drives in a parallel filesystem?
> Data storage drives in a parallel filesystem?
>
> Over on the CEPH mailing list there are regular topics on
> choice of SSDs. I would advise going over there and asking
> the same question.
>
> Also you don't say how they are failing.
> Are these consumer grade drives or data centre grade drives?
> Consumer drives have much, much lower 'drive writes per day'
>
> Two jobs ago I would have said the go-to data centre
> drives were Intel.
>
> Also one comment specific to HPC. I found that SSD drives
> dont 'get sick' like spinning drives,
> ie you dont see syslog messages about blocks failing to be
> read/written. They just fail.
> Also two jobs ago I though that SMART checks were not
> picking up failing SSDs.
> I believe that you can monitor them if you choose the
> correct counters. Anyone?
>
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> On 22 July 2018 at 07:32, Jonathan Aquilina
> <jaquilina at eagleeyet.net <mailto:jaquilina at eagleeyet.net>>
> wrote:
>
> What Ones are you currently getting?
>
> Sent from my iPhone
>
> > On 22 Jul 2018, at 05:42, Jonathan Engwall
> <engwalljonathanthereal at gmail.com
> <mailto:engwalljonathanthereal at gmail.com>> wrote:
> >
> > I am not happy with the SSDs I am using. I am buying
> another sad every couple weeks.
> > Fast sure, but my productivity right now is zero.
> > Are there any recommendations on reliable ssd brands?
> > Jonathan Engwall
> > _______________________________________________
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