My Jellyfin just quivered…
I’ve been looking to buy a couple 24TB drives. Hopefully, this pushes their price down.
When will it be commercially available though? Supposedly Seagate has had 30TB drives out for the better part of a year, but I can’t find anything larger than 24TB actually available for purchase.
Obligatory hint that SMR isn’t suited for RAID systems.
A better way to word it is: SMR is only suited for archival usage. Large writes, little-to-no random writes.
If you know the format of SMR, then you can trivially see the read performance is not impacted. Writing is impacted, because it has to write multiple times for each sector write (because of overlapping sectors that allow the extra density).
Impacted write performance, coupled with hdds are generally slow with random writes PLUS the extra potential for data loss due to less-atomic sector writes, makes them terrible drives for everything except archival usage.
Wonder what happens if you throw them in an unraid BTRFS/jbod configuration with a CMR parity drive.
Assuming that these have fairly impressive 100 MB/s sustained write speed, then it’s going to take about 93 hours to write the whole contents of the disk - basically four days. That’s a long time to replace a failed drive in a RAID array; you’d need to consider multiple disks of redundancy just in case another one fails while you’re resilvering the first.
That’s a pretty common failure scenario in SANs. If you buy a bunch of drives, they’re almost guaranteed to come from the same batch, meaning they’re likely to fail around the same time. The extra load of a rebuild can kill drives that are already close to failure.
Which is why SANs have hot spares that can be allocated instantly on failure. And you should use a RAID level with enough redundancy to meet your reliability needs. And RAID is not backup, you should have backups too.
My 16TB ultrastars get upwards of 180MB/s sustained read and write, these will presumably be faster than that as the density is higher.
I’m guessing that only works if the file is smaller than the RAM cache of the drives. Transfer a file that’s bigger than that, and it will go fast at first, but then fill the cache and the rate starts to drop closer to 100 MB/s.
My data hoarder drives are a pair of WD ultrastar 18TB SAS drives on RAID1, and that’s how they tend to behave.
This is for very long sustained writes, like 40TiB at a time. I can’t say I’ve ever noticed any slowdown, but I’ll keep a closer eye on it next time I do another huge copy. I’ve also never seen any kind of noticeable slowdown on my 4 8TB SATA WD golds, although they only get to about 150MB/s each.
EDIT: The effect would be obvious pretty fast at even moderate write speeds, I’ve never seen a drive with more than a GB of cache. My 16TB drives have 256MB, and the 8TB drives only 64MB of cache.
2 parity is standard and should still be adequate. Likelihood of two failures within four days on the same array is small.
