shanemikel
Dabbler
- Joined
- Feb 8, 2022
- Messages
- 49
How does ZFS provide durability given the multi layer caches involved in storage systems?
First, I'm using HDDs with onboard caches. Unlike with SSDs I see mentioned around here, which must have power loss protection, the HDDs AFAIK don't have this circutry. Does ZFS somehow tell disks not to use onboard cache? If so, I may as well save money and buy drives with smaller cache size, all else being equal.
Second, HW RAID controller caches pose a threat to durability, which is why they typically come with an integrated backup battery. OK, we're using ZFS, so IT mode HBA instead of RAID controller. I haven't read anything here about integrated batteries, so I'm assuming HBAs don't have caches and RAID card caches are disabled when flashed into IT mode?
Assuming I follow the recommendations about disk types & sizes, RAIDZ config, etc. can I run this thing confidently without UPS & how so?
First, I'm using HDDs with onboard caches. Unlike with SSDs I see mentioned around here, which must have power loss protection, the HDDs AFAIK don't have this circutry. Does ZFS somehow tell disks not to use onboard cache? If so, I may as well save money and buy drives with smaller cache size, all else being equal.
Second, HW RAID controller caches pose a threat to durability, which is why they typically come with an integrated backup battery. OK, we're using ZFS, so IT mode HBA instead of RAID controller. I haven't read anything here about integrated batteries, so I'm assuming HBAs don't have caches and RAID card caches are disabled when flashed into IT mode?
Assuming I follow the recommendations about disk types & sizes, RAIDZ config, etc. can I run this thing confidently without UPS & how so?