True or False

[henry1006]

Someone told me if i go with ZFS, the hdd storage will be cut in half for redudency purposes. is that true?

If i set of ZFS and there are times where i need the whole hdd, can i take it out by shut down and unpluging sata cable?

Will there still be redudency if i don't run raid in ZFS.

my budget is limited but i have alot of essential data

 

[Yatti420]

Please start with the documentation.
Docs.freenas.org

Sent from my SGH-I257M using Tapatalk 2

 

[danb35]

Short answer: false.
Longer answer: it depends.

If you set up a ZFS pool without a RAIDZ or mirror configuration, and you don't specify one of the "copies=2+" options, then you will not lose any (significant amount) of your capacity. You will also have no redundancy. To gain redundancy, you have to sacrifice capacity in one form or another. You can do that either by configuring a RAIDZ device (which requires at least 3 drives, can have 1, 2, or 3 drives' worth of redundancy, and correspondingly loses 1, 2, or 3 drives' worth of capacity), by setting up a mirror (which does lose half of your capacity, but tolerates the failure of half of your drives), or by using the "copies=2" (or =3 or more) option (which stores however many copies you specify of your data on your drive--it will tolerate bad sectors, but a drive failure will still kill it).

 

[henry1006]

so if a drive fail with the second choice(mirroring), then the data will be killed?

and what about my second question "If i set of ZFS and there are times where i need the whole hdd, can i take it out by shut down and unpluging sata cable?"

 

[henry1006]

then all the data will be killed*

 

[danb35]

If you have a mirror, say with two drives, and one drive fails, your data is safe on the other drive. However, the capacity of your pool will be the capacity of one drive, not both. If you have a redundant configuration (mirror or RAIDZ) and detach one drive for use elsewhere, you retain your data, but lose redundancy. If another drive then fails, you may lose all your data.

 

[henry1006]

ok, I see now. thanks and I understand this is RAID 1 which I fully know about but will all the sata port in the motherboard have to have RAID1 capability?
im planning on putting 8HDD running RAID1 therefore I have total of 4TB, I don't think all 8 sata ports have RAID 1 capability b/c 6 ports are run by a chip and the other 2 are run by the cpu

 

[danb35]

Motherboard RAID capability is irrelevant and should not be enabled. The docs, and cyberjock's PowerPoint in the "New to FreeNAS" forum, will further address this.

 

[henry1006]

Im still confused, so to have 2 hdd be mirrored. it will have to be based on ZDev? so its software things to do not hardware side?

also if I later want to end FreeNAS and go to a proper windows server, I will have to remove all the data before I take out a hdd so my zpool won't fail?


Lasatly, it talks about propery shut down but what if there was a power outage(rarely[<once a year])? should I also get a power surge adapter?(again rarely)

 

[ser_rhaegar]

In addition to reading the docs as Yatti420 suggested, also check out cyberjocks slideshow: http://forums.freenas.org/index.php...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/

 

[henry1006]

I did read the powerpoint which made things a bit clearer

 

[danb35]

FreeNAS is a software package that runs on commodity PC hardware. All of the data handling, including RAID implementation, is done in software, not in hardware. If you stop using a proper FreeNAS server and want to migrate to Windows for some reason, the health of your ZFS pools won't be an issue, as you won't be using them any more. Windows can't read ZFS, so you'll need to move your data to drives formatted with a filesystem that Windows can read (probably NTFS).

If you set up 8x 1 TB drives as mirrors, they'll likely be four two-disk mirrors, striped together. That will give you, as you stated, about 4 TB of usable capacity. You can lose up to four drives with no data loss, if they're the "right" four drives--you can only lose one drive from each mirror set. If you happen to lose both drives of one mirror set, your entire pool will fail.

Consider instead setting these drives up in a RAIDZ2 pool. This will give about 6 TB of usable capacity, and any two drives can fail without loss of data. The number of disks isn't optimal, but the loss of performance will likely be minimal.

You should use a UPS to avoid unplanned power loss to any server, and a FreeNAS server is no exception. With ZFS, it's unlikely that you'll have filesystem corruption in the event of a power outage, but it's still best avoided.