![]() The principles behind ZFS can be found in many enterprise storage systems like NetApp. I have no confirmation, but Sun started developping ZFS the same time to adress exact these problems like a crash resistent filesystem or checksums to be able to repair verified data from redundancy. ![]() Filesystems from that time are simply not good enough for current storage capacities. In 2016 even a tablet or laptop may have more storage than the Sun cluster at that time so you must face similar problems with any storage. Another internet provider was well advised to use hundreds of smaller independent servers instead one large storage to avoid large storage problems. Reason was a crash/powerloss in a Sun storage cluster with the unability to repair via several fschk where each needs some days to run and the lack of a most current backup or the needed time to restore others from backup. SOFTRAID RAID 6 OFFLINEIt was in 2001 when about a third of all german internet sites were offline for a week with a complete dataloss on many of them. Optionally you can add an SSD to extend the readcache but this is much slower than RAMbased caching. Some ZFS systems have 64-512 GB RAM what means that most or nearly all reads for current data are delivered from RAM. More is faster as it is used as Readcache. Oracle where ZFS is native with a 64bit Solaris claims a minumum of 2GB for ZFS solutions with any poolsize. Even with dozens of disks in a ZFS Raid-Z2/3 CPU load is not really relevant today.Ĥ GB RAM is ok for ZFS. The little raid calculation does not matter. With enough RAM and a modern CPU this is even faster than a hardwareraid with less and slower RAM. A nice extra are snaps and the advanced cache mechanism and sync write options that are part of ZFS. So the best solution would be not using Raid-6 with ext4 but using ZFS with a more robust raid than Raid-6 and with a better overall datasecurity due checksums and CopyOnWrite. No partly updated filesystem or raid-arrays - 100% crash resistent by design. The other solution are softwareraid and CopyOnWrite filesystems as there a write is done completely (data, metadata, raidstripe) or not at all. One is a hardware raidcontroller + BBU that can reduce the problem. ![]() There are two common ways to handle this. "Write hole" phenomenon in RAID5, RAID6, RAID1, and other arrays. This is due the write hole problem on Raid-6 On a crash during a write you are in danger of a corrupted filesysten and/or raid array. Not only is this much faster, it’s less error-prone, especially when you’re working with 4 or more drives.With any Raid-6 solution, does not matter if softwareraid or hardwareraid, a raid stripeset is written disk by disk sequentially. SoftRAID lets you select all the desired hard drives, then in one step make a RAID set of the desired type and total size (no mental gymnastics required). Perhaps the best feature of SoftRAID is faster and easier creation of RAID sets-none of the confusing Disk Utility nonsense of having to partition first, then make a RAID set out of the partitions. SOFTRAID RAID 6 DRIVERSoftRAID is a multi-threaded “filter” driver (one thread per CPU), and under heavy loads it can offer significantly higher performance than Apple’s single-threaded Disk Utility driver.Ī forthcoming version of SoftRAID will offer a single-threaded option (checkbox), to work around bugs in other flaky components this can be a (rare) issue today with certain hardware. Can delete volumes on a drive without affecting other volumes on the same drive. ![]()
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