6 Mar
2020
6 Mar
'20
3:38 a.m.
Hi,
Does someone know if the following harddisk has a decent performance in
a ceph cluster:
Micron 5210 ION 1.92TB, SATA (MTFDDAK1T9QDE-2AV1ZABYY)
The spec state, that the disk has power loss protection, however, I'd
nevertheless like to make sure that all goes well with this disk.
Best Regards,
Hermann
--
hermann(a)qwer.tk
PGP/GPG: 299893C7 (on keyservers)
6 Mar
6 Mar
3:45 a.m.
That depends on how you define “decent” , and your use case.
Be careful that these are QLC drives. QLC is pretty new and longevity would seem to vary
quite a bit based on op mix. These might be fine for read-mostly workloads, but
high-turnover databases might burn them up fast, especially as they fill up.
On Mar 5, 2020, at 12:38 PM, Hermann Himmelbauer
<hermann(a)qwer.tk> wrote:
Hi,
Does someone know if the following harddisk has a decent performance in
a ceph cluster:
Micron 5210 ION 1.92TB, SATA (MTFDDAK1T9QDE-2AV1ZABYY)
The spec state, that the disk has power loss protection, however, I'd
nevertheless like to make sure that all goes well with this disk.
Best Regards,
Hermann
--
hermann(a)qwer.tk
PGP/GPG: 299893C7 (on keyservers)
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2:33 p.m.
I have just ordered two of them to try. (the 3.47GB ION's)
If you want, next week I could perhaps run some commands on them..?
MJ
On 3/5/20 9:38 PM, Hermann Himmelbauer wrote:
> Hi,
> Does someone know if the following harddisk has a decent performance in
> a ceph cluster:
>
> Micron 5210 ION 1.92TB, SATA (MTFDDAK1T9QDE-2AV1ZABYY)
>
> The spec state, that the disk has power loss protection, however, I'd
> nevertheless like to make sure that all goes well with this disk.
>
> Best Regards,
> Hermann
>
4:01 p.m.
Last monday I performed a quick test with those two disks already,
probably not that relevant, but posting it anyway:
I created a two-disk ceph 'cluster' on just the one local node, and ran
the following:
root@ceph:~# rados bench -p scbench 10 write
--no-cleanup
hints = 1
Maintaining 16 concurrent writes of 4194304 bytes to objects of size 4194304 for up to 10
seconds or 0 objects
Object prefix: benchmark_data_ceph_48906
sec Cur ops started finished avg MB/s cur MB/s last lat(s) avg lat(s)
0 0 0 0 0 0 - 0
1 16 107 91 363.961 364 0.0546517 0.155121
2 16 206 190 379.948 396 0.1529 0.159227
3 16 324 308 410.614 472 0.0972163 0.151421
4 16 458 442 441.942 536 0.0484349 0.141799
5 16 590 574 459.141 528 0.0445051 0.136922
6 16 727 711 473.941 548 0.181066 0.134468
7 16 856 840 479.941 516 0.187683 0.133199
8 16 970 954 476.942 456 0.070753 0.132642
9 16 1089 1073 476.831 476 0.193608 0.133754
10 16 1214 1198 479.142 500 0.0999212 0.132529
Total time run: 10.097218
Total writes made: 1215
Write size: 4194304
Object size: 4194304
Bandwidth (MB/sec): 481.321
Stddev Bandwidth: 60.481
Max bandwidth (MB/sec): 548
Min bandwidth (MB/sec): 364
Average IOPS: 120
Stddev IOPS: 15
Max IOPS: 137
Min IOPS: 91
Average Latency(s): 0.132889
Stddev Latency(s): 0.0645579
Max latency(s): 0.336118
Min latency(s): 0.0117049
Do let me know what else you'd want me to do.
MJ
8:06 p.m.
Hi,
Current QLC drives are total shit in terms of steady-state performance.
First 10-100 GB of data is written into the SLC cache which is fast, but
then the drive switches to its QLC memory and even the linear write
performance drops to ~90 MB/s which is actually worse than with HDDs!
So, try to run a long linear write test and check the performance after
writing a lot of data.
> Last monday I performed a quick test with those two disks already,
> probably not that relevant, but posting it anyway:
10:40 p.m.
But is random/sequential read performance still good? even during saturated write
performance ?
if so the tradeoff could fit quite some applications
Sent from myMail for iOS
Friday, 6 March 2020, 14.06 +0100 from vitalif <vitalif(a)yourcmc.ru>ru>:
Hi,
Current QLC drives are total shit in terms of steady-state performance.
First 10-100 GB of data is written into the SLC cache which is fast, but
then the drive switches to its QLC memory and even the linear write
performance drops to ~90 MB/s which is actually worse than with HDDs!
So, try to run a long linear write test and check the performance after
writing a lot of data.
Last monday I performed a quick test with those
two disks already,
probably not that relevant, but posting it anyway:
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7 Mar
7 Mar
1:53 a.m.
Hi,
Sure, I will try the fio as requested by Marc Roos. I will be onsite
again monday/tuesday. If you have a good way to test/show what you
describe below, don't hesitate to post it here.
I'll try it when I have the time.
Are you saying that the write performance becomes bad (90MB/sec) for
long lasting *continuous* writing? (after filling up a write buffer or such)
But given time to empty that buffer again, it should again write with
the normal higher speed?
So in applications with enough variation between reading and writing,
they could still perform good enough?
MJ
On 3/6/20 2:06 PM, vitalif(a)yourcmc.ru wrote:
> Hi,
>
> Current QLC drives are total shit in terms of steady-state performance.
> First 10-100 GB of data is written into the SLC cache which is fast, but
> then the drive switches to its QLC memory and even the linear write
> performance drops to ~90 MB/s which is actually worse than with HDDs!
>
> So, try to run a long linear write test and check the performance after
> writing a lot of data.
>
>> Last monday I performed a quick test with those two disks already,
>> probably not that relevant, but posting it anyway:
3 a.m.
Yes. The drive treats some portion of cells as SLC, which having only two charge states
is a lot faster and is used as cache. As with any cache-enabled drive, if that cache
fills up either due to misaligned flush cycles or simply data coming in faster than it can
flush, you’ll see a performance cliff.
Also, uniquely for reasons I don’t yet understand, as the drive fills up, the size of that
cache area decreases linearly until it hits a certain minimum. Thus an empty drive will
have more cache in service than a 70% full drive.
This article includes 8x10 color glossy pictures with circles and arrows and a paragraph
on the back describing what each one is about.
https://www.howtogeek.com/428869/ssds-are-getting-denser-and-slower-thanks-…
Which raises some interesting questions about the proper use of TRIM both by RBD clients
and by ceph-osd, especially when dmcrypt is used.
— aad
Are you saying that the write performance becomes bad
(90MB/sec) for long lasting *continuous* writing? (after filling up a write buffer or
such)
But given time to empty that buffer again, it should again write with the normal higher
speed?
So in applications with enough variation between reading and writing, they could still
perform good enough?
MJ
On 3/6/20 2:06 PM, vitalif(a)yourcmc.ru wrote:
Hi,
Current QLC drives are total shit in terms of steady-state performance. First 10-100 GB
of data is written into the SLC cache which is fast, but then the drive switches to its
QLC memory and even the linear write performance drops to ~90 MB/s which is actually worse
than with HDDs!
So, try to run a long linear write test and check the performance after writing a lot of
data.
> Last monday I performed a quick test with those two disks already,
> probably not that relevant, but posting it anyway:
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1520
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7 comments
5 participants
participants (5)
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Anthony D'Atri -
Hermann Himmelbauer -
jesper＠krogh.cc -
mj -
vitalif＠yourcmc.ru