Alex Gardiner
2015-01-01 17:36:04 UTC
Hello list,
Is anybody else is using ZFS on Linux to store and stream video files?
In my case I am serving half a dozen streams between 100-200Mbps and offering them to my lab over SMB/AFP.
Although traditionally I have used hardware solutions by 3ware and HP, both of which boast cache profiles and firmware that claim to be optimised for this use case, I wonder if there are any equivalent approaches for ZFS?
From the HP documentation about "Video on Demand":
http://h20565.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c00687518
“Decreasing the maximum latency of block requests to the Smart Array is one of the key goals for VOD…. Other improvements include changing the cache ratio to be 0 % read and 100 % write. Since VOD operations are 99% random, any read-ahead operation would penalize performance. You want to post the writes so that they have the least impact on the reads”
Spec wise my lab box is a 2U Supermicro 825TQ running an 8 drive Z2 (4TB WD RED/LSI 9211-8i/16GB ECC). Actually, the performance is pretty impressive right out of the box, it just feels too easy :-)
From what I can see video streaming workloads do not seem to benefit all that much from adding lots of ARC (at least not much beyond what I already have). Similarly due to the shape of this kind of workload, L2ARC/SLOG do not seem to be especially effective, although can save some IOPS with smaller files.
Ultimately what I am asking is should I just relax and trust ZFS to be smart, or can you think of any specific tunings that may be useful?
Many thanks and all the best for 2015.
Alex
PS. I have not been brave enough to use SATA discs with a SAS port expander due reading a few horror stories. Am I still right to avoid this as much as possible?
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Is anybody else is using ZFS on Linux to store and stream video files?
In my case I am serving half a dozen streams between 100-200Mbps and offering them to my lab over SMB/AFP.
Although traditionally I have used hardware solutions by 3ware and HP, both of which boast cache profiles and firmware that claim to be optimised for this use case, I wonder if there are any equivalent approaches for ZFS?
From the HP documentation about "Video on Demand":
http://h20565.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c00687518
“Decreasing the maximum latency of block requests to the Smart Array is one of the key goals for VOD…. Other improvements include changing the cache ratio to be 0 % read and 100 % write. Since VOD operations are 99% random, any read-ahead operation would penalize performance. You want to post the writes so that they have the least impact on the reads”
Spec wise my lab box is a 2U Supermicro 825TQ running an 8 drive Z2 (4TB WD RED/LSI 9211-8i/16GB ECC). Actually, the performance is pretty impressive right out of the box, it just feels too easy :-)
From what I can see video streaming workloads do not seem to benefit all that much from adding lots of ARC (at least not much beyond what I already have). Similarly due to the shape of this kind of workload, L2ARC/SLOG do not seem to be especially effective, although can save some IOPS with smaller files.
Ultimately what I am asking is should I just relax and trust ZFS to be smart, or can you think of any specific tunings that may be useful?
Many thanks and all the best for 2015.
Alex
PS. I have not been brave enough to use SATA discs with a SAS port expander due reading a few horror stories. Am I still right to avoid this as much as possible?
To unsubscribe from this group and stop receiving emails from it, send an email to zfs-discuss+***@zfsonlinux.org.