So while I am playing around with my new build I wondered whether a NVMe drive would be a good slog device.
I have read @jgreco's recommendation for P3700 (or Intel 750) alternatively but haven't seen anyone actually testing them.
So I dont have a 750 but I have an Samsung 950 pro/512MB drive. I know its not a recommended disk due to missing superconductor. But after all its playing around only so what the heck.
My primary use case will be vmware/nfs so I thought I'd run a pretty basic test (not scientific at all), but I am quite suprised at the result - the 950 pro is way slower then expected.
I have run a simple copy from one esx datastore (locally, Samsung Evo 850) to one of three nfs attached
datastores
Datastore 3_SASSSD points to a mirror of HGST SAS 400GB SSDs
Datastore 3_nvme points to a single Samsung 950 pro as datastore
Datastore 3_tank points to a 2x2 mirror of NL-Seagate 7200 2GB SAS HDDs, with another SAS 400GB SSD as SLOG
[root@solesx2:/vmfs/volumes] ls -ltr EVO_850_512/W2k12/W2k12-flat.vmdk
-rw------- 1 root root 42949672960 Nov 7 2016 EVO_850_512/W2k12/W2k12-flat.vmdk
[root@solesx2:/vmfs/volumes] time cp -R EVO_850_512/W2k12/W2k12-flat.vmdk 3_SASS
real 7m 3.09s
user 1m 2.84s
sys 0m 0.00s
[root@solesx2:/vmfs/volumes] time cp -R EVO_850_512/W2k12/W2k12-flat.vmdk 3_nvme/
real 22m 14.83s
user 1m 7.47s
sys 0m 0.00s
[root@solesx2:/vmfs/volumes] time cp -R EVO_850_512/W2k12/W2k12-flat.vmdk 3_tank/
real 7m 19.29s
user 1m 25.72s
sys 0m 0.00s
So despite beating all other disks in speed by at least double (reached >1GB/s with the nvme drive) it does not seem to be a good SLOG device at all (and yes i know high transfer speed does not make a good slog device;))
I now wonder whether this is only the cheapo Samsung and if somebody has tested the Intel 750 with more sucess?
Edit:
Just for completeness sake here is the samsung as slog on the tank pool
[root@solesx2:/vmfs/volumes] time cp -R EVO_850_512/W2k12/W2k12-flat.vmdk 3_tank
/
real 21m 28.50s
user 1m 27.42s
sys 0m 0.00s
I have read @jgreco's recommendation for P3700 (or Intel 750) alternatively but haven't seen anyone actually testing them.
So I dont have a 750 but I have an Samsung 950 pro/512MB drive. I know its not a recommended disk due to missing superconductor. But after all its playing around only so what the heck.
My primary use case will be vmware/nfs so I thought I'd run a pretty basic test (not scientific at all), but I am quite suprised at the result - the 950 pro is way slower then expected.
I have run a simple copy from one esx datastore (locally, Samsung Evo 850) to one of three nfs attached
datastores
Datastore 3_SASSSD points to a mirror of HGST SAS 400GB SSDs
Datastore 3_nvme points to a single Samsung 950 pro as datastore
Datastore 3_tank points to a 2x2 mirror of NL-Seagate 7200 2GB SAS HDDs, with another SAS 400GB SSD as SLOG
[root@solesx2:/vmfs/volumes] ls -ltr EVO_850_512/W2k12/W2k12-flat.vmdk
-rw------- 1 root root 42949672960 Nov 7 2016 EVO_850_512/W2k12/W2k12-flat.vmdk
[root@solesx2:/vmfs/volumes] time cp -R EVO_850_512/W2k12/W2k12-flat.vmdk 3_SASS
real 7m 3.09s
user 1m 2.84s
sys 0m 0.00s
[root@solesx2:/vmfs/volumes] time cp -R EVO_850_512/W2k12/W2k12-flat.vmdk 3_nvme/
real 22m 14.83s
user 1m 7.47s
sys 0m 0.00s
[root@solesx2:/vmfs/volumes] time cp -R EVO_850_512/W2k12/W2k12-flat.vmdk 3_tank/
real 7m 19.29s
user 1m 25.72s
sys 0m 0.00s
So despite beating all other disks in speed by at least double (reached >1GB/s with the nvme drive) it does not seem to be a good SLOG device at all (and yes i know high transfer speed does not make a good slog device;))
I now wonder whether this is only the cheapo Samsung and if somebody has tested the Intel 750 with more sucess?
Edit:
Just for completeness sake here is the samsung as slog on the tank pool
[root@solesx2:/vmfs/volumes] time cp -R EVO_850_512/W2k12/W2k12-flat.vmdk 3_tank
/
real 21m 28.50s
user 1m 27.42s
sys 0m 0.00s
Last edited: