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Is there any limitation on USB HDD with ReadyNAS OS6?
Dear All
any one got the USB HDD compatibility list?
I've a RN626X and wanna to buy a 8TB /10TB USB drive for backup
Thanks
gn00347026 wrote:
seems there's no limitation on the USB HDD, just avoid to use SMR, right?
There might some limitations. I know of at least one person who had to format their USB drive in a PC in order to access all the space. I use other ReadyNAS for backup myself, not USB drives.
Generally it's useful to search on the model in the forum before purchasing drives, and see if any other users have have shared their experience. Google is one convenient way to do that (using site:community.netgear.com in the search string).
8 Replies
I have no specifics on this, but I do suggest avoiding SMR drives. Many larger seagate USB models are SMR.
One option is to back up over the network to a USB drive attached to a PC. That might be a bit slower than native backup on the RN626X (smallnetbuilder.com measured USB 3.0 NTFS backup speed at ~ 120 MB/sec). And of course it requires the PC to be on when the backup is made.
One benefit is that Windows and OSX handle drive ejection better than linux. Plus it ensures that a NAS failure can't corrupt the backup.
Hello
Do you mind expanding on why you would steer clear of SMR drives?
Thanks
paulmt wrote:
Do you mind expanding on why you would steer clear of SMR drives?
Sure.
The tracks on an SMR drive are overlapped, so when you write to track N, the write operation also trashes track N+1.
The drive overcomes this by reading track N+1, writing track N, reading track N+2, writing track N+1, etc. Eventually it reaches the end of a zone (where there are unused tracks), so it can stop "rippling" the write. The drive firmware has no idea of the format, so it can't stop early (because as far as it knows, all the tracks have data).
There are a lot of optimizations in the drive firmware to overcome the obvious performance problems. The drives have a large cache, and I believe they will try to re-order writes so that the "rippling" is minimized. Even with the optimizations, the write performance will slow to a crawl during sustained writes. SMR drives also don't always sleep when they are told to (so the write rippling will proceed). I'm not sure how well they handle unexpected ejection or power loss - certainly you have to depend on the drive maintaining the cache and its write state properly no matter what happens to the power.
The technology is certainly cost-effective, and it is good for archival. I don't recommend it for daily backup jobs though, especially with a linux OS (which doesn't handle USB drives as gracefully as windows or OSX already).
SMR technology is also used in Seagate archival internal drives. Some users here used archival drives in the ReadyNAS when they were first introduced, though I haven't seen any posts from people using then lately. Results were mixed - partly due to the performance challenges noted above, and partly due to driver problems. Seagate does not (and never has) recommended them for RAID.
to paulmt - No prolbem ^^
seems there's no limitation on the USB HDD, just avoid to use SMR, right?
Thanks and regards
Tony
gn00347026 wrote:
seems there's no limitation on the USB HDD, just avoid to use SMR, right?
There might some limitations. I know of at least one person who had to format their USB drive in a PC in order to access all the space. I use other ReadyNAS for backup myself, not USB drives.
Generally it's useful to search on the model in the forum before purchasing drives, and see if any other users have have shared their experience. Google is one convenient way to do that (using site:community.netgear.com in the search string).
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