Best disk configuration for Plex

[zetabax]

Hi Community,

If I understand the physics correctly, larger disks can reduce overall performance.

With that, I'm running running Plex on an SSD in TrueNAS with media files stored on 12x 4 TB 7200 SAS drives in Z3.

I'm running out of space and looking at replacing the drives with larger disks (ie 8 TB or maybe even 12 TB disks)

I have been collecting media for nearly 20 years and the quality ranges from 420 all the way up to 4K.

Would love to hear about your experiences with larger drives.

Thanks!

 

[jgreco]

Larger drives store more data.

The seek speed of the 1GB HDD from 25 years ago is not much different than the seek speed of the 20TB HDD of today, while the space factor has changed by 20,000. That 20TB drive will have about thirty-nine BILLION sectors, and if you had to fill that one sector at a time with a seek in between each, and you could clear 200 IOPS reliably, it would take you about 2260 days to fill the drive, or about the expected lifespan of the HDD. That's your physics analysis there.

For that reason, we no longer consider HDD's as particularly good for random read/write workloads; HDD's are better off used for applications where there are large sequential runs of data, where seeks are not the dominating performance issue.

RAIDZ is highly optimized for the storage of large sequentially accessed files and is very efficient at it.

7200 RPM drives are "performance" drives which attempt to target applications needing fast response time, especially faster seeks. They run hotter, vibrate more, and have shorter lifespans compared to their 5400/5900 RPM kin. If we accept the premise that RAIDZ and HDD should be used for large sequential files, where there should not be a need for lots of seeks, then it should become clear that the value of 7200 RPM drives may be questionable in a RAIDZ configuration, unless there is an extremely demanding concurrent access pattern.

So I say all of this to frame the following comments;

1) You may wish to avoid the 7200 RPM drives in the future.

2) You may also wish to avoid SAS drives in the future. SATA HDD's, especially shuckables, are often available at a lower cost. If you are sticking these into a disk shelf with an SAS expander backplane, SATA should work as well as SAS.

3) The cost differential going from 8 to 12TB is modest and it may be better to be able to push off an upgrade from 8 to 12 by just jumping to the 12's or larger. Arrays with large contiguous regions of free space also tend to be a little faster.

4) Please be sure to avoid SMR HDD's