Author here - i wrote this article to collect some thoughts after seeing a lot of breathlessly positive reviews of ZFS. I hope my criticism comes across as being written with love - ZFS is a highly accomplished filesystem - but it didn't invent these features, and you can have better performance elsewhere.
re: No disk checking tool (fsck) - you didn't mention the "zpool scrub" command.
Also the IOPS of RAIDZ is, as you said, about the same as a single disk - but only for writes. For reads, it scales fairly linearly like a RAID0.
It is definitely good that you outline all these shortcomings, since people need to know what it is bad at as well as good at. However I think you are wrong that compression and checksumming are "usually not worthwhile" - surely it depends? I've found the compression to be excellent for VM disk images (unlike deduping). And the checksumming has been invaluable in large HDD arrays built with cheap consumer-grade disks. With a large enough array, the usual CRC system can sometimes fail to detect errors.
2 comments
[ 3.2 ms ] story [ 18.7 ms ] threadHappy to answer any comments,
Also the IOPS of RAIDZ is, as you said, about the same as a single disk - but only for writes. For reads, it scales fairly linearly like a RAID0.
It is definitely good that you outline all these shortcomings, since people need to know what it is bad at as well as good at. However I think you are wrong that compression and checksumming are "usually not worthwhile" - surely it depends? I've found the compression to be excellent for VM disk images (unlike deduping). And the checksumming has been invaluable in large HDD arrays built with cheap consumer-grade disks. With a large enough array, the usual CRC system can sometimes fail to detect errors.