Disk configuration for a home/office system

[keylevel]

I'm trying to work out an optimal solution for a home/office NAS that will mainly be used to store PC backups and media files (mainly pictures).

Aims are:

1. Fast writes (so backups don't take for ever);
2. Fast reads;
3. Ability to survive multiple disk failures;
4. Reasonable storage costs.

I was thinking of using:

1. A three disk mirror using (e.g.) 1TB Seagate FireCuda hybrids (8 GB flash, 128 MB Buffer). This should give reasonable write performance (due to the 8 GB flash) and resilience.
2. A 500 GB SSD as an L2ARC to give fast read support (working set will fit in this - will upgrade when needed and/or prices come down).

Does this make sense?

 

[Stux]

FWIW, mirrors write at the speed of a single disk. Where as RaidZ writes at the speed of then data width. (Well, technically this is true of both I guess)

I'm not sure if the flash based hybrid drives are a good idea or not, they're not exactly designed for NAS usage.

I guess my point is a 4-way Raidz2 will write at double the speed of a 3way mirror, and have the same redundancy. And double the capacity. If NAS drives are 25% cheaper than hybrid drives, then that may be better and equivalent in price

Are you planning on backing up via SMB?

Re: l2arc, how much ram are you planning to use?

 

[keylevel]

I though I read on here somewhere that RAIDz2 doesn't write any faster? I'll have to go and re-read.

Backup will mainly be Time Machine (AFP), other access will be AFP and SMB. As an aside, the NAS itself will be backed up by replicating to an external HDD rotation set.

I'm currently getting about 105 MB/s on to a single SSD using a very hacked-together lash-up. This has shown me that FreeNAS is the way to go (much faster than the very old ReadyNAS I've got) - I now need to put a proper system together. I would like to use all SSD, but I can't justify the cost...

 

[Stux]

RaidZ2 does sequential writes faster. Normally you compare a single Raidz2 against multiple mirrors, each mirror writes at the speed of a single disk.

BUT multiple mirrors has more IOPS than Raidz2.

Anyway, SMB/AFP is async traffic, so no slog needed.

 

[keylevel]

Doh! That'll teach me to stay up too late - I was thinking of a pool with two mirrors in it.

 

[MrToddsFriends]

I'm currently getting about 105 MB/s on to a single SSD using a very hacked-together lash-up.

Gigabit Ethernet won't be able to give you substantially more than that. Are you planning to use something faster?

 

[keylevel]

No, that's fast enough for sitting in the home office ;-) Currently lucky to get 30 MB/s with what I've got.