I’m considering two Toshiba enterprise-class hard drives MG09 series 18 TB, vs. MG10 series 20 TB) from OWC, and would appreciate any advice on the better choice for reliability, and if 4K vs 512e sector is better. I’ve always bought enterprise-class drives for reliability. I’m leaning toward the 20 TB with 512 sectors.
Both are the same 10^16 bits reliability (according to Toshiba’s spec sheets), CMR, and have a 5-year warranty. The 18TB has 9 platters, the 20TB has 10 platters. There was a time when more platters was considered less reliable, but maybe that doesn’t matter now? Both use “Toshiba Flux Control Microwave-assisted Magnetic Recording (FC-MAMR)” and are helium-sealed. I know the very first helium drives had issues several years ago, and I hope that’s solved now.
An OWC sales rep said the MG10 has “newer technology that may offer better long-term reliability and performance”. It’s a newer model, so maybe they improved something.
Lastly, I’ve always bought 512e sector models for compatibility, instead of 4k sector. Maybe 512 is still best overall, but I can’t find any documentation on where the compatibility comes into play with macOS. This drive would be used on an Intel Mac Pro 5,1 internal bay (Mojave and Monterey), and later Apple Silicon. Thanks for any advice.
I’d say that either one should work great. But watch out for the 20TB MG09, with is SMR.
Also make sure your enclosure can provide adequate cooling. I assume a Mac Pro can, but I have no personal experience. Passive cooling is not appropriate for a high performance drive.
I’ve never used a drive with 4K blocks, out of a concern that it may be incompatible with system software, but it appears that modern operating systems all have support these days. According to a Western Digital white paper:
Old operating systems that access 512 byte blocks will lose performance for single-block updates, since the drive will have to read a 4K block, modify part of it, then write the entire block. (I don’t know if Toshiba’s enterprise drives support 512-byte block emulation.)
I believe GPT-partitioned devices always use 4K logical blocks. And since you need GPT partitioning for drives larger than 2TB anyway, that should be fine.
The WD white paper goes on to say that macOS 10.4 and later supports 4K file systems and automatically aligns partitions when creating a GPT partition on a 4K drive.
Although it won’t be the case for your installation in a Mac Pro, if you choose to put a 4K drive in an external USB enclosure, you must make sure its bridge chip supports drives with 4K blocks. Otherwise the drive will work in 512-byte emulation mode, hurting performance.
I don’t think you’re going to find any better source of information on hard drive reliability that what Backblaze publishes.
And obviously their use case is going to be different than yours.
David C is correct about the 20 TB MG09s being SMR. The Toshiba MG09 web page is a bit unclear on that, at one point saying they are CMR but if you drill down to individual models does say they are SMR.
Whether SMR is a problem or not depends on your use. I use some SMR drives in an array that is mostly read, rarely needs writes and have had no trouble with them. I’ve found some web sites that claim SMR has some reliability advantages but don’t know how well founded in “truth” those claims may be.
I actually recently purchased several drives to back up all my personal data that were 18 TB MG09 drives. They were factory recertified drives and after two solid weeks of writing to them they have thrown no SMART errors.
I run my drives in a Q30
and the drives rarely exceed 32C and usually are <30C but I agree that if you run many of them in a small case you need active cooling for them.
Thanks David and Kevin, I appreciate any and all advice. I hadn’t noticed the SMR variable, something I would rather avoid. I think I’m leaning to the MG10 series 20 TB which appears to not have that.
The Western Digital white paper is interesting on 512 byte blocks vs 4K. If it’s accurate, macOS has supported 4K blocks since OS 10.4, which is rather a long time. Although it says, "Even when using a 4K operating system, it is possible for individual applications to ignore OS settings and attempt to write in 512-byte blocks. With 512-byte emulation, these applications will continue to work. " I wish Apple published something themselves. Maybe I’ll get the 512 byte version just to be safe.
Applications never see blocks at all. They read and write files, which are managed by the OS. If your volume is partitioned and formatted with 4K blocks, then that’s what will be used.
Can an application choose to read a file 512 bytes at a time? Of course, but it can also choose to read it 128 or 10 bytes at a time. The operating system should deal with things like this.
It is possible that you could partition a disk with 4K blocks and then format one partition with a file system that only recognizes 512 byte blocks. That might cause the emulation to kick in. But that shouldn’t be an issue if you’re using a modern file system like APFS, HFS+ or NTFS. If you’re trying to format it with something old like FAT, that might be an issue.
Disk utilities, which may be making SATA block-access calls directly, would need to be able to deal with 4K blocks. If you use utilities like these, you may want to contact the publisher to see if they will be compatible.
If 512-byte-block drives are available for the same price as the 4K-block device, I’d also use the 512-byte-block drive, just because of my own uncertainty, even if it might reduce performance by a small amount. But since (I assume) you have a particular use-case in mind, you might just want to buy the 4K-block drive from a store with a good return policy, run some acceptance tests, and exchange it if you find problems.
Thanks again David. I’ll be formatting the drive with HFS+ for my primary daily-use data (no macOS), although I suppose I could set that to APFS as well despite reduced performance.
I’ve been hesitant to use APFS on a hard drive, since DiskWarrior doesn’t support it, and I don’t think there are any other repair utilities that do. My impression is APFS might be more reliable, but with only Disk Utility to rely on, it’s not very comforting. If the drive works out, I’ll buy a 2nd one to use for Time Machine and use APFS in that case.
Backblaze is a good source for drive reliability as Kevin suggested, and Toshiba has positive results there, although they don’t have the newer MG09 or MG10 models, or anything larger than 16 TB. Hopefully choosing the newer model 20 TB with one extra platter will be as safe as the older 18 TB. It all seems like a bit of luck.
FWIW, my backup devices (yes, I know, only three of them) are Toshiba 4TB N300 NAS drives. I’m using them in generic USB 3.0 enclosures, not in a NAS.
They work well, but I found that I needed to get enclosures with cooling fans, because they run too hot for a passive-cooling enclosure, and they pretty much stop working when they overheat. I suspect this will be the case for all 7200 RPM and high capacity drives.