tag:blogger.com,1999:blog-37798047.post5317041391842279847..comments2024-01-16T05:48:33.523-05:00Comments on Errata Security: NAS buying criteria for the home cloudDavid Maynorhttp://www.blogger.com/profile/09921229607193067441noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-37798047.post-35639258636497612572012-07-23T15:01:00.743-04:002012-07-23T15:01:00.743-04:00I'm very happy with FreeNAS 8.2 running on an ...I'm very happy with FreeNAS 8.2 running on an HP Proliant Microserver. The CPU (AMD Athlon II Neo N36L) supports ECC RAM. I also added an Intel PCI-E NIC which noticeably sped up file transfers.Joehttps://www.blogger.com/profile/14998755598722686389noreply@blogger.comtag:blogger.com,1999:blog-37798047.post-78585351841202820782012-07-19T07:03:43.976-04:002012-07-19T07:03:43.976-04:00Be careful about "simple" solutions - li...Be careful about "simple" solutions - like reading all the files on a RAID periodically to force error correction. They can make things worse. It's hard to visualize the effects of really rare events; you need to model them. People have (there was a nice paper a couple of years back, but I don't have a ready reference). <br /><br />The firmware in a modern disk can have 1-2 million lines of code. Do you think it's bug-free? One *observed* failure mode is: You write data to block A, but it's actually written to block B on the disk. Now think about what this does to a RAID. Block A and block B are parts of redundancy groups RA and RB, which (say) are parts of files FA and FB. After the bad write, both RA and RB have an incorrect block in them. But neither block reports an error when read - at the level of the individual block, it contains valid data. A RAID that recovers based entirely on disk read errors will happily deliver incorrect data in this situation. Even a RAID-6, which is supposed to survive two errors, is at a loss.<br /><br />One can prevent this by adding more redundancy - e.g., writing the block number into the block itself, or doing higher-level checksums. ZFS does this kind of thing; so do enterprise-level RAID boxes. Historically, the algorithms have been ad hoc and the modeling and simulation showed that *all* the published approaches had error paths that would lead to silent data corruption - and those that tried to "heal" bad data could be induced to "heal" it into a permanently bad value that would then be completely undetectable. As I recall, ZFS was among the better solutions, though it had failures, too. Perhaps now that the analysis techniques are out there, better solutions have been developed - but I haven't seen anyone pushing them, so maybe not.<br /><br />Anyway ... take RAID storage for what it's worth: A (much) more reliable alternative to individual disks, but not a *perfect* alternative. Personally, I use my RAID box as a target for backups. So live data is redundantly stored on the original system and on the RAID box. Old, deleted files are only on the RAID box so are less redundant - but also less likely to be needed. (And, actually, I make a separate backup of the most important files to an ioSafe box, which isn't RAID - in fact, I just had the single disk in it go bad; ioSafe replaced it - but it *is* protected against various physical issues like house fires and theft. The backups to the ioSafe are done using CrashPlan, so have their own internal redundancy. I may add some cloud backup to the mix, too. Layering, redundancy, disjoint failure modes - ultimately, they are the only way you get robustness.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-37798047.post-71287151930762636362012-07-18T19:54:16.700-04:002012-07-18T19:54:16.700-04:00Loved the entry. Been doing home NAS for many yea...Loved the entry. Been doing home NAS for many years now. I prefer Thecus. The sweet spot for me has been 4.5TB of RAID5 and XFS support on the N4100Pro. TwonkyMedia also creates a great "bridge" between my Windows Media Center(PC) + Xbox360 + various Apple devices. People also need to consider a backup for their NAS. 2TB drives are easy to get now, but in 5 years = dinosaur bones.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-37798047.post-35247447994962243782012-07-18T19:27:53.395-04:002012-07-18T19:27:53.395-04:00Setting up FreeNAS takes less time than writing th...Setting up FreeNAS takes less time than writing this article.<br /><br />Drobo is shit that does not work. Don't fall for their marketing, or be prepared to lose your data.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-37798047.post-8487491250576327012012-07-18T09:33:31.774-04:002012-07-18T09:33:31.774-04:00Drobo also makes the DroboFS, which is network att...Drobo also makes the DroboFS, which is network attached storage. I have had the Drobo gen2 and now the DroboFS. It works nice for my purposes: set it and forget it. Its the Ron Popeil of NAS devices.1n4001https://www.blogger.com/profile/06673904060346939948noreply@blogger.comtag:blogger.com,1999:blog-37798047.post-77921698754447097112012-07-18T02:54:14.316-04:002012-07-18T02:54:14.316-04:00something else troubling about the WD greens that ...something else troubling about the WD greens that I found out the hard way is that they have insanely aggressive head-park timers and there's an old DOS firmware tool that allows you to remove most of these sort of "green" features.<br /><br />A worst case scenario (happened at times on my FBSD/geli/graid3 NAS before I made the switch to ZFS) would occur that went something like d1(write->park), d2(wake,write->park), d3(wake->write->park) literary getting several years worth of head park cycles in the course of a month or two before failing.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-37798047.post-61761799665978344522012-07-17T18:59:33.792-04:002012-07-17T18:59:33.792-04:00ZFS would be my preferred choice, especially becau...ZFS would be my preferred choice, especially because of things like the write-hole and health checking, and also because of things like the lack of ECC memory on Atom CPUs. A box based on a notebook CPU should provide low-power near that of an Atom, but be a lot faster for things like encryption (with the built-in AES instructions).<br /><br />But that would take several days setting up the hardware and learning how to do ZFS. I've got enough boxes demanding my time for sysadmin work, I don't need yet another.Robert Grahamhttps://www.blogger.com/profile/09879238874208877740noreply@blogger.comtag:blogger.com,1999:blog-37798047.post-22350847789929740032012-07-17T18:09:23.480-04:002012-07-17T18:09:23.480-04:00Or you could make the smart choice: build a PC (or...Or you could make the smart choice: build a PC (or use an old one), put something like FreeNAS. You get ZFS and encryption.<br /><br />You even went with a NAS that uses an Atom, which is widely available.lolnoreply@blogger.com