I know and i won't be using zfs on hardware raid anyway. My issue here is
hardware compatibility as i don't have enough sata ports to run my disks on
my motherboard. Either i run pure hardware raid or hba + zfs, just need to
be sure of the card.
zfs performance cost is not an issue when you have a high end desktop imo.
2016-02-01 18:39 GMT+01:00 Gordon Messmer <gordon.messmer(a)gmail.com>:
On 02/01/2016 08:33 AM, thibaut noah wrote:
> Yeah i saw some build reviews on freenas, they recommend ecc but it is
> not mandatory (and actually after reading some tests i don't get all the
> fuss on ecc ram).
>
Just as with disks, bits can flip in RAM. Probably the most important
feature of ZFS is checksums on all blocks so that bit flips can be detected
and repaired. ECC RAM does the same for memory. If you don't have ECC
RAM, and bits flip in memory, you're likely to silently corrupt data.
Saw that too and i don't get it, i mean, what the hell? You can replace
> disks with bigger one but you'll have all this trouble if you want to
> expand the array? That doesn't feel right.
>
The same is true of any disk array, I'd think. If you replace a disk, you
need to rebuild the array. The array size is determined by the smallest
member in the array. Given those two constraints, there's nothing unusual
about the process.
Thing is spending 600+$$ on a nas doesn't seem worth it compared to buying
> an high end raid card.
>
ZFS (and btrfs) and hardware RAID are not, in my opinion, comparable.
RAID arrays don't keep checksum information on each block, so if a bit
flips they don't have a means of reliably repairing it. ZFS can repair bit
flips. You probably don't want to use ZFS on hardware RAID, since many of
ZFS' features rely on accessing each disk individually. A battery backed
write cache can be useful, but I don't think it's better than having a UPS
that's monitored.
Also it's either having a second case or buying a dual system case which
> cost more than 500$$, those guys...
> Spending much money on a raid card also seem like spending money for
> nothing too as it seems i'll have better performances with hba card + zfs
> that using a raid card. (did some research meanwhile)
>
It's possible, but I don't think that's necessarily true. ZFS' features
come at a performance cost, in general.
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