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113

RAID: Why and When RAID stands for Redundant Array of Independent Disks (some are taught "Inexpensive" to indicate that they are "normal" disks; historically there were internally redundant disks which were very expensive; since those are no longer available the acronym has adapted). At the most general level, a RAID is a group of disks that act on the ...


55

ZFS will give you advantages beyond software RAID. The command structure is very thoughtfully laid out, and intuitive. It's also got compression, snapshots, cloning, filesystem send/receive, and cache devices (those fancy new SSD drives) to speed up indexing meta-data. Compression: #zfs set compression=on filesystem/home It supports simple to create ...


45

Congratulations and uh-oh. You've stumbled across one of the better things about ZFS, but also committed a configuration sin. First, since you are using raidz1, you only have one disk worth of parity data. However, you had two drives fail contemporaneously. The only possible result here is data loss. No amount of resilvering is going to fix that. Your ...


28

Also RAID ONE MILLION!!!! 128 Disks so reads would be fast, horrible writes but very reliable I'd imagine, oh and you'd get 1/128th the available space, so not great from a budgetary perspective. Don't do this with flash drives, I tried and set fire to the atmosphere...


27

I've built a number of these "all-in-one" ZFS storage setups. Initially inspired by the excellent posts at Ubiquitous Talk, my solution takes a slightly different approach to the hardware design, but yields the result of encapsulated virtualized ZFS storage. To answer your questions: Determining whether this is a wise approach really depends on your ...


25

For ZFS, there are number of factors which contribute to the overall cost, performance and your satisfaction with the system you've built. SUPPORTABILITY If you need to be able to call someone when you have problems don't DIY, buy a Sun 7000 Unified Storage appliance. They're a little pricey, but you get what you pay for. High quality hardware, with ...


24

I've found XFS more well suited to extremely large filesystems with possibly many large files. I've had a functioning 3.6TB XFS filesystem for over 2 years now with no problems. Definately works better than ext3, etc at that size (especially when dealing with many large files and lots of I/O). What you get with ZFS is device pooling, striping and other ...


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I was confused by this at the beginning as well. Since the ZFS is referring to 'Storage pools', the author created the nickname 'Tank' as in a 'Tank of water' or a 'Fish tank'. It is a bit of a play on words since the English words 'Pool' and 'Tank' both refer to large containers of water. Some people find it confusing at first. Here is an old example from ...


23

Why, hello there Lars! That's a fascinating question you've asked, and after some research I may have found an answer for you. According to this and other posts out there, it may be possible to set the VFCF_JAIL attribute on the NFS filesystem provider, which would in theory allow jails to perform NFS mounts. This may, in turn, allow one to run amd inside ...


20

See this thread from one of the FreeBSD lists: http://lists.freebsd.org/pipermail/freebsd-fs/2009-June/006327.html To quote Dan Naumov, To reiterate, you cant just add a single disk drive to a raidz1 or raidz2 pool. This is a known limitation (you can check with SUN ZFS docs). If you have an existing raidz and you MUST increase that particular ...


19

Design the right way and you'll minimize the chances of data loss of ZFS. You haven't explained what you're storing on the pool, though. In my applications, it's mostly serving VMWare VMDK's and exporting zvols over iSCSI. 150TB isn't a trivial amount, so I would lean on a professional for scaling advice. I've never lost data with ZFS. I have experienced ...


17

Most of these snapshots are copy-on-write snapshots, which are really fast and really cheap (storage-wise) on rarely-updated systems. LVM snapshots are COW snapshots, ZFS/BTRFS both have a COW-mode for snapshots, reiserfs doesn't have snapshots natively, Novell's NSS file-system is also COW, as are Shadow Copy volumes for Windows NTFS volumes. Copy-on-write ...


16

As of April 2010 Btrfs is still in development and not ready for production use (really, it isn't - I have been bitten experimenting with kernel 2.6.32). Feature-wise btrfs contains some but not all of ZFS features. Most notably RAID-Z and data deduplication are missing. What does work with btrfs is snapshotting, copy-on-write, checksumming and using ...


14

Offline drive #1. Replace the old drive with the newer, high-capacity drive. zpool replace the drive. Wait for the replacement to be rebuilt. Goto step 1 and repeat for each successive drive in the array. You may need to export and then import the zpool once this procedure is complete; the pool will then show the increased size. No downtime is required, ...


14

Don't know about the speed, but here is what I believe running ZFS on RAID would means: You loose the benefits of atomic writes because now the RAID controller has the last say on when a write happens to the disk. Which means you rely on the RAID controllers NVRAM. ZFS also may get lied to if the data was written inporperly, ZFS would have to take the ...


14

I hope this is gonna help a little. I tried to not let it turn into a full wall of text. :) 3Par/Isilon If you can and will dedicate a fixed amount of man-hours for someone who takes the SAN admin role and wanna enjoy a painless life with night-sleep instead of night-work then this is the way I'd go. A SAN lets you do all the stuff where a single ...


14

Yes, ZFS doesn't need hardware raid and is actually better when used without it. It is able to provide partial data protection even with a single device when configured to use ditto blocks but of course won't resist a full disk failure in that case. You can use it in a mirror configuration (two devices or more) or a RAIDZ one (three devices or more) to ...


13

This has been solved. They key is that deduplicated volumes need to have the dedup flag turned off before deletion. This should be done at the pool level as well as the zvol or filesystem level. Otherwise, the deletion is essentially being deduplicated. The process takes time because the ZFS deduplication table is being referenced. In this case, RAM helps. I ...


13

I build a home FreeBSD file server using ZFS. It is an AMD X2 3200+ with 3GB of RAM. It has a PCI Express Gig-E. The boot drive is an old 400GB and I have 4 750GB Seagte drives (one with a difference firmware version, just in case). Booting from ZFS would have been nice (it would make install simpler), but I used the ZFSOnRoot instructions to setup the ...


13

using lvm snapshots and xfs on live filesystems is a recipe for disaster especially when using very large filesystems. I've been running exclusively on LVM2 and xfs for the last 6 years on my servers (at home even since zfs-fuse is just plain too slow)... However, I can no longer count the different failure modes I encountered when using snapshots. I've ...


13

you probably already figured that the linux fuse zfs is a toy. Nexenta is based on opensolaris but got debian apt-get. you can try this. personally I think OpenSolaris is fine, takes a while to get used to - but worth the effort.


13

ZFS was released with the CDDL license, so it cannot ever be built in to the Linux kernel. It is possible to install ZFS on Ubuntu, and several people have released howto documents. If you Google search for "ZFS Ubuntu" you find several. Here's one: http://systembash.com/content/howto-installing-zfs-and-setting-up-a-raid-z-array-on-ubuntu/ ZFS on Ubuntu ...


12

We've pushed a Sun X4100 writing over bonded GigE and iSCSI to an Sun X4500 to 280MB/s. There's a lot that can be done to tune the TCP stack on Solaris to help things out, this my my stock tuning config. (take from some collection of Sun whitepapers): $ cat /etc/rc3.d/S99ndd #!/bin/bash NDD=/usr/sbin/ndd $NDD -set /dev/tcp tcp_xmit_hiwat 1048576 $NDD ...


12

Basically there's three types of ZFS cache, all used for both data and metadata. ARC (Adaptive Replacement Cache) - Main memory DRAM cache for reads and writes. L2ARC (Level 2 ARC) - safe read cache: no data loss/service interruption from device failure. Usually SSD based. ZIL (ZFS Intent Log) - safely holds writes on permanent storage which are also ...


12

I'd really recommend you take a look at ZFS, but to get decent performance, you're going to need to pick up a dedicated device as a ZFS Intent Log (ZIL). Basically this is a small device (a few GB) that can write extremely fast (20-100K IOPS) which lets ZFS immediately confirm that writes have been synced to storage, but wait up to 30secs to actually commit ...


12

The -F switch comes in handy if you have messed with the destination dataset after it has been received. Once you do any changes to it (including doing something as innocent as a directory listing as this would change atimes), it is no longer in the state it was in after the initial transfer. Trying to run a plain zfs receive from an incremental data stream ...


12

Please don't do this. If you're going to run ZFS on Linux, do it bare metal without a virtualization layer. All-on-one virtualization and ZFS solutions are cute, but it's not worth the effort in production. As far as drives are concerned, you can use SATA disks on an HP Smart Array controller as well as the LSI 9211-8i controller. In a ZFS configuration, ...


12

FreeNAS is a NAS solution, as such, some technical choices are hidden behind whatever firmware, system or GUI such appliance can use. If you get the partition schema used on a given disk inside a ZFS pool made with FreeNAS (small VM example): $ glabel status Name Status Components ...


12

I think you should reconsider your use of FreeNAS. You've had an uncharacteristically. large. number. of issues. with. your. FreeNAS. installation(s). over. the years. Many of these issues were planning and ZFS design problems. It may be time to refactor or rebuild your environment now that you have some knowledge of best or better-practices.



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