4 ms·

> what's the lowest power hardware solution with acceptable performance? Depends what you define as acceptable. RAID-1 (as in mdadm) is fairly low on CPU requi

by darkr 11y ago

> what's the lowest power hardware solution with acceptable performance? Depends what you define as acceptable. RAID-1 (as in mdadm) is fairly low on CPU requirements, generally something like an Intel atom chipset (late cedarview chipsets have a TDP around 6.5w) should give reasonable performance, otherwise a mobile/low end i3 would give even better performance.

pjc50 11y ago
Would there be any advantage to running ZFS on that pair of disks in that situation? I hear it has much more demanding requirements including memory/disk ratio.
- darkr 11y ago
  If you're just using it as "dumb" storage, then ZFS gets you block-summing, so better data integrity guarantees - but in order to rely on that you need ECC RAM, which means a server-class CPU (and more $$$ for RAM). The Avoton range of Atoms do support this (I'm potentially looking at getting an 8-core one myself in the next 6 months). Other than that, if you're not planning to exploit any of ZFS's functionality, and are looking to deploy on as cheap hardware as possible, mdadm RAID1 (with LVM over the top) is just the ticket. If you need to expand, just add another mirrored pair, assign it a physical volume, add that to the volume group, expand your logical volume, then expand your filesystem (ext4 supports online resize and is very stable, XFS is also a solid contender). All of this is fairly boring compared to ZFS, but it works and it works well..
  - benjaminl 11y ago
    When a block of data on a mirrored disk goes bad, mdadm won't be able to fix it and often doesn't even know that the data is bad. Since there is a mirrored copy this a correct copy of your data but since there is no metadata or checksums, mdadm has no way to tell which is correct. ZFS will silently detect the corruption and will rewrite the data restoring the duplicate copy of the data again. All this works great without ECC RAM, recent studies of data corruption have shown that RAM is much more reliable then previously thought. ECCisnt needed for ZFS for home use.
  - swinglock 11y ago
    You don't strictly need ECC RAM to run ZFS any more than you do when running other filesystems, the issues that comes with a bad stick of RAM will just become more obvious which is not a bad thing. It's just assumed that if you run ZFS you do care about getting the same data out that you put in, so it's highly recommended. Bottom line is, ZFS without ECC isn't worse than other filesystems without ECC.

by darkr 11y ago

pjc50 11y ago

Would there be any advantage to running ZFS on that pair of disks in that situation? I hear it has much more demanding requirements including memory/disk ratio.

darkr 11y ago
If you're just using it as "dumb" storage, then ZFS gets you block-summing, so better data integrity guarantees - but in order to rely on that you need ECC RAM, which means a server-class CPU (and more $$$ for RAM). The Avoton range of Atoms do support this (I'm potentially looking at getting an 8-core one myself in the next 6 months). Other than that, if you're not planning to exploit any of ZFS's functionality, and are looking to deploy on as cheap hardware as possible, mdadm RAID1 (with LVM over the top) is just the ticket. If you need to expand, just add another mirrored pair, assign it a physical volume, add that to the volume group, expand your logical volume, then expand your filesystem (ext4 supports online resize and is very stable, XFS is also a solid contender). All of this is fairly boring compared to ZFS, but it works and it works well..
- benjaminl 11y ago
  When a block of data on a mirrored disk goes bad, mdadm won't be able to fix it and often doesn't even know that the data is bad. Since there is a mirrored copy this a correct copy of your data but since there is no metadata or checksums, mdadm has no way to tell which is correct. ZFS will silently detect the corruption and will rewrite the data restoring the duplicate copy of the data again. All this works great without ECC RAM, recent studies of data corruption have shown that RAM is much more reliable then previously thought. ECCisnt needed for ZFS for home use.
- swinglock 11y ago
  You don't strictly need ECC RAM to run ZFS any more than you do when running other filesystems, the issues that comes with a bad stick of RAM will just become more obvious which is not a bad thing. It's just assumed that if you run ZFS you do care about getting the same data out that you put in, so it's highly recommended. Bottom line is, ZFS without ECC isn't worse than other filesystems without ECC.