Western Digital recently announced new data center HDDs that increase Shingled Magnetic Recording (SMR) capacity to 32TB and Conventional Magnetic Recording (CMR) capacity to 26TB. The company...
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.
This is one of the reasons I use unRAID with two parity disks. If one fails, I’ll still have access to my data while I rebuild the data on the replacement drive.
Although, parity checks with these would take forever, of course…
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.
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.
2 parity is standard and should still be adequate. Likelihood of two failures within four days on the same array is small.
This is one of the reasons I use unRAID with two parity disks. If one fails, I’ll still have access to my data while I rebuild the data on the replacement drive.
Although, parity checks with these would take forever, of course…
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.