New to RaidZ and ZFS. Need Advice

Ultim8 · 26 Mar 2011 at 14:49

OK so im new to linux based raid.
Im building a custom freenas box and also have a hp microserver which i would also like as a NAS.

I want speed and redundancy so i know the custom box will easily be capable of running ZFS and raidz as its spec is as follows:

Zotac H55ITX-C-E
I3 530
2 x 2GB 7-7-7-20 1333Mhz OCZ
4 x 2TB 7200RPM Hitachi Deskstars
1 x 2.5" 7200RPM drive for Freenas
Chenbro ES34169

The HP Microserver is:

AMD Athlon II Model NEO N36L (2 core, 1.30 GHz, 1MB L2, 15W)
2 x 2GB
4 x 1TB Seagate 7200.12
1 x 2.5" 7200RPM Drive for Freenas

Now will the HP be able to run raidz and ZFS?

Also i want to lose as little as possible space (1 disk) but what raidz do i need to use to accomplish that?

Ultim8 · 27 Mar 2011 at 19:46

nobody know this?

kg648 · 27 Mar 2011 at 20:09

raid5 i guess?

kg648 · 27 Mar 2011 at 20:11

4 disks @2tb will give you roughly 5.5TB of usable storage.

4 disks @1tb will give you roughly 2.7TB of usable storage.

daz · 27 Mar 2011 at 21:55

Raid Z is equivalent to RAID5. The only issue is your rebuilt time. Under ZFS/Solaris this is called 'resilvering', but when a drive fails, the array will be in a degraded state until you replace the failed drive and rebuild/resilver the array. When using 1TB drives, depending on how you fill them, the rebuild time could easily be a day. During that time, if you have another drive failure, (possible if your drives came from the same batch and have been exposed to identical conditions) then you would lose all of your data.

For this reason, for drives 1TB or larger, and for data that is important to you I would recommend RAID Z2 (RAID 6). If losing your data isn't a big deal (or you have good backups to recover from) then the small (but real) chance of a second drive failure during the rebuild might not be a big deal, but it is something to think about.

Al Vallario · 27 Mar 2011 at 23:12

I'm running a raidz1 (RAID5 equivalent, as has been stated) array with 4x 2TB drives in an HP MicroServer running FreeBSD (FreeNAS being based on FreeBSD).

Works perfectly. If you have any specific questions I'll be happy to help

Ultim8 · 28 Mar 2011 at 08:16

Thanks guys, Al Vallario whats your transfer rates like?

Ultim8 · 28 Mar 2011 at 12:42

also i hear that its better to run raidz on an odd number of drives, is this correct?

Al Vallario · 28 Mar 2011 at 16:16

Ultim8 said:
Thanks guys, Al Vallario whats your transfer rates like?

My zpool status (4x 2TB Samsung drives, only 5400RPM, not the fastest in the world):

Code:

freebsd# zpool status data
  pool: data
 state: ONLINE
 scrub: none requested
config:

	NAME        STATE     READ WRITE CKSUM
	data        ONLINE       0     0     0
	  raidz1    ONLINE       0     0     0
	    ad4     ONLINE       0     0     0
	    ad6     ONLINE       0     0     0
	    ad8     ONLINE       0     0     0
	    ad10    ONLINE       0     0     0

errors: No known data errors

Testing write speed (/data is the ZFS mount), about 120MB/sec:

Code:

freebsd# dd if=/dev/zero of=/data/test.file bs=4M count=1000 conv=notrunc 
1000+0 records in
1000+0 records out
4194304000 bytes transferred in 35.024325 secs (119754028 bytes/sec)

Using the built-in ZFS NFS server (sharenfs) over a gigabit wired network, I have tended to get about 20-30MB/sec writing transfers. Reading I tend to get 30-40MB/sec.

I only have the standard 1GB RAM though; apparently ZFS performs better with more. Likewise, I don't have jumbo frames enabled on my network, which could see you squeeze a nice bit extra out of the transfer rate

Ultim8 · 28 Mar 2011 at 16:49

thanks for that mate, so with 4gb of ram and 7200rpm drives i may be able to saturate my gigabit network as long as the raidz isnt too much for the CPU.

I want to turn the zotac box into a multitude of boxes using VM if possible you see. So if the HP can handle raids and ZFS and get me to saturate my network then i can do that.

s0ck · 1 Apr 2011 at 13:45

What drive have you got in the client PC? 40MB/s read seems a bit low? Would it perform better, natively, under Solaris maybe?

Jumbo frames don't yield a huge bandwidth benefit from the tests I've seen. I don't have the link to hand but one guy was getting well over 900Mb/s with the standard frame size, it's just he was getting closer to 1Gb/s with 9k MTU.

Ultim8 · 1 Apr 2011 at 21:59

right guys i have got the HP microserver up and running tonight and upgraded it to 4GB.
Installed Freenas 8 RC4 onto a usb drive and have created a volume using 3 x 2tb drives as ZFS and raidz.....now what?

in volumes i see /mnt/HP NAS now but it seems i need to do something else to enable it.
I configured CIFS to my network but from my windows pc's i cant see the nas.

Please post responses in my new dedicated thread for this.