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25

Snapshotting a filesystem is an amazing feeling, as geeky as that sounds. Knowing you can roll back in an instant is a relieving thought. Snapshots also take only a few seconds. A colleague and I recently deployed an OpenSolaris NAS for a smallish college (200+ students) for virtual machine iSCSI storage for Citrix XenServer, student file storage and ...


25

In Addition to what was said before by grawity and Paul: History In the "old days", cpio (with option -c used) was the tool to use when it came to move files to other UNIX derivates since it was more portable and flexible than tar. But the tar portabilityissues may be considered as solved since the late 1980s. Unfortunately it was about that time that ...


18

Both tar and cpio have a single purpose: concatenate many separate files to a single stream. They don't compress data. (These days tar is more popular due to its relative simplicity – it can take input files as arguments instead of having to be coupled with find as cpio has.) In your case, you do not need either of these tools; they would have no ...


10

I'd say "very", since files are encrypted with AES in CCM mode (by default). However, AES per se is not a guarantee, much depends on how it is implemented. And there is this sentence in the documentation that makesmade me wonder: Review the following considerations when using the ZFS compression, deduplication, and encryption properties: When a file ...


10

zfs-win GNU GPL v2 requires Dokan … read-only drive can be mounted … — and I guess that further development might enable write access. Following installation on Windows 7: Microsoft Windows [Version 6.1.7601] Copyright (c) 2009 Microsoft Corporation. All rights reserved. C:\Users\Administrator>chdir "C:\Program Files (x86)" c:\Program Files ...


7

ZFS in virtual machine can work just fine if follow one simple rule never ever lie to ZFS. ZFS goes to great length to keep your data from getting corrupted (checksums, copy-on-write, dittoblocks, mirrors or raid-z, etc) so you should do everything in your power to let ZFS directly access your disks. All the horror stories of virtualized ZFS issues come ...


7

If by NAS you mean (Open)Solaris or FreeBSD on PC hardware acting as a fileserver, then yes, it should be fine. See this question on building your own NAS. You might find dedicated NAS software such as FreeNAS easier to setup and admin.


6

Some things you need to worry about are: The architecture. Pools created on x86 wont be importable by SPARC and reciprocally unless you are using whole disks (EFI labels) as vdevs instead of slices. The OpenSolaris release. If the destination server is using an older release of OpenSolaris, it will likely be impossible to successfuly import the pool and/or ...


6

I wrote a blog article for Super User about my ZFS-based NAS, which I built about a year ago. I'd strongly recommend ZFS - the article summarises the main benefits for a NAS, and here's a good detailed description of ZFS's features (see the show notes, and from about 28 minutes into the video). I get satisfactory performance with a 2008 dual-core Atom CPU, ...


5

What you're referring to as a tank is really a ZFS pool and your datasets are ZFS filesystems within the pool. ZFS deduplication has pool-wide scope and you can't see the dedup ratio for individual filesystems. If you turn dedup on for a pool that already contains data, the existing data will not be automatically deduped and your ratio will still be 1.00x. ...


5

It's been a while since I played with zfs, but you should be able to use zfs list -t snapshot to find your available snapshots and access the files under a special .zfs directory under your zfs mountpoint. [~]# zfs list -t snapshot NAME USED AVAIL REFER MOUNTPOINT mypool 1.49G 527M 528M /mnt/zfspool ...


5

http://www.osnews.com/story/22388 Apple discontinued their ZFS project unfortunately. This was announced back in October and they removed the official mailing lists and repositories.


5

As of yet, there isn't a way to convert zpool structures. Also, there isn't a way to expand a RAIDz. To my knowledge, RAIDz is something you have to setup from the start. That said, there is an exception. If you have three disks in a RAIDz configuration, basically one disk is used for redundancy. You can concatenate zpools so you can create a second ...


5

You can get deduplication overall statistics with the zdb -D poolname command. For per file compression status, it's not very straightforward but you might use this: zdb dataset | grep plain This will output lines looking like these ones: 8 2 16K 128K 3.03M 5.00M 100.00 ZFS plain file 9 2 16K 128K 3.03M 5.00M 100.00 ZFS ...


5

A method some people use, but that is not recommended: Create a pool with 2 drives and a sparse file (of the right, virtual size to match the other drives), and then immediately offline the sparse file. This will create a degraded RAID-Z1 pool with two drives worth of capacity and no redundancy. Copy data to the degraded pool. Replace the offlined ...


4

This is possible with RAID-Z, as described by the ZFS Administration Guide: When a replacement device that is greater in size than the device it is replacing is added to a pool, is not automatically expanded to its full size. The autoexpand pool property value determines whether a pool is expanded to its full size when the disk is added to the pool. By ...


4

Unfortunately, at the moment it is not possible: It is not possible to add a disk as a column to a RAID-Z, RAID-Z2, or RAID-Z3 vdev. This feature depends on the block pointer rewrite functionality due to be added soon. One can however create a new RAID-Z vdev and add it to the zpool. RAID-Z1 might work with just 2 drives, but clearly this is not very ...


4

Here is something close to what you are looking for, although you would need to be root to achieve it: $ dd if=/dev/zero of=/home/user/qqq.zfs bs=1M count=100 # zpool create -O compression=gzip -m /home/user/mnt qqq /home/user/qqq.zfs # chown user /home/user/mnt ZFS supports non root operations (i.e. delegation) but ZFS-FUSE doesn't implement them.


4

The ZFS Uberblock is the root of a giant dynamic tree whose leaves contain data. Most other file systems use instead a superblock (and copies of it) and a static collection of fixed size inode maps. There are no inode maps with ZFS, inode equivalents (dnodes) are dynamically created and destroyed.


4

The purpose of the tree is to improve data integrity, partly by storing checksums away from the data blocks those checksums protect. The entire file system hierarchy forms a self-healing hash tree, or merkle tree. Here's a simplified description I made earlier: Going from left to right, directory 1 contains a pointer to file A, file A's checksum, ...


4

Perhaps this isn't an answer to your question directly, but my own experience has been that typical NAS hardware costs about the same as a regular PC. The only reason you might get NAS vs a PC is its lower physical profile. We evaluated the NAS vs PC question quite a bit and eventually ended up with PC, because it has significantly more flexibility for us. ...


4

Use format to get a list of the available harddisks. rpools are special. Their disks must not have an EFI label. You can delete the EFI label with format/fdisk. You don't have to format the drive before adding it to a zpool. But in case of rpools you need to copy the partition layout from the first to the 2nd disk. The commands you've mentioned are correct ...


4

I've been using FreeBSD 8.0 and subsequently 8.0-stable-February 2010 snapshot to experiment with ZFS for a couple of months. The system has a couple of independent 4-disc RAIDZ1 pools. At first things seemed to go more or less perfectly, though I've run into some increasingly disturbing problems which makes me think that under some particular ...


4

The majority of the team has left since the oft-cited ZFS project at macosxforge.org shut down. Check here for the "refugees" and latest code, although it's clearly not well supported.


4

FreeBSD and OpenSolaris seem to be the best choices for hosting ZFS With OpenSolaris, ZFS is usually versions/features/bug-fixes ahead. OpenSolaris' hardware support is nowhere near as good as e.g. Ubuntu Hardware support is getting much better with recent OpenSolaris builds but as long as your hardware is supported that shouldn't really matter. ...


4

ZFS on a home NAS is great. I've have a FreeBSD server running ZFS for years (now upgraded to FreeBSD 8.2 with V15) and the recover aspects are one of the hidden gems. I have a system that has a pair of 2TB drives in a ZFS mirror that crashed due to environmental reasons, when it came back up, it only took seconds for ZFS to correct the issues with drive. ...


4

While ZFS will use as much memory as it thinks useful to cache stuff, it will give it back to applications should there is demand for it. Note that other file systems will also take as much memory as they need as cache. The main difference is that memory is immediately available for applications. With ZFS, there is a slight delay but that should make no ...


4

1: there is no problem changing anything. The pool should be importable regardless of the CPU, mainboard or anything similar. 2: ZFS works best with devices of the same size. Moreover, as you want redundancy, devices larger than the smallest one would have their extra size wasted. Finally, you cannot add a device (eg: the 4 TB disk) to a RAIDZ. If you only ...


4

What happens if I have to change the underlying hardware behind the zfs pool? Like the mobo / processor, what happens if that dies on me in a year or two; can I port my zfs pool somehow? A ZFS pool is not hardware dependent. Just make sure your HBA (Host Bus Adapter) isn't doing something like encrypting your data at the hardware level. ZFS works ...


4

If you are using zfs-fuse, just running the zfs-fuse init script on startup should do it. I have several computers with zpools on external disks and they are all mounted automatically on boot with zfs-fuse. In particular, the init script contains the line zfs mount -a which mounts all available zfs filesystems. You could add this line to any zfs init ...



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