Microsoft Storage Spaces for Desktop Benchmarked

After NAS mirror upgrade I ended up with two spare Barracuda 7200.14 hard drives.  Given that I am running out of space on my video editing workstation, the choice was clear.  Would be nice though if I could use those in a mirror - to make sure things are fast and tolerate hard drive failure.  I just learned about Microsoft Storage Spaces and throught I would give it and ReFS a try.

I compared I/O performance of three drives:

• Kingston SSDNow V300 Series SV300S37A/120G 2.5" 120GB SATA III SSD - just because it was already there.
• Single hard drive - 2861589GB Seagate Barracuda 7200.14 (AF) ST3000DM001-1E6166 
• A Microsoft Windows 8.1 Storage Space with two of the above hard drives configured as mirror.

Here is what I measured using CrystalDiskMark 3.0.3 x64:

	MB/s	IOPS	MB/s	IOPS	MB/s	IOPS	Delta
Sequential Read:	446.836		140.259		181.808		22.85%
Sequential Write:	144.154		137.572		125.443		-8.82%
Random Read 512KB:	404.102		50.204		39.758		-20.81%
Random Write 512KB:	144.021		82.208		66.927		-18.59%
Random Read 4KB (QD=1):	22.666	5533.8	0.386	94.3	0.449	109.6	14.03%
Random Write 4KB (QD=1):	108.644	26524.5	6.93	1692	0.382	93.2	-94.49%
Random Read 4KB (QD=32):	116.621	28471.9	0.468	114.3	0.456	111.2	-2.56%
Random Write 4KB (QD=32):	141.824	34624.9	0.983	239.9	0.384	93.7	-60.94%
	SSD		1x Barracuda 7200.14		2x Barracuda 7200.14

Transition to storage spaces mirror moderately improves sequential read speed.  Random write performance however is dramatically deteriorated.  For a workstation use scenario this makes storage spaces unacceptable for me.  They may still be relevant for servers.

So I will be sticking with two single hard drives.  Maybe will use synchtoy to backup one drive to another.

Mirror Upgrade - Step by Step, the Right Way

The last time I tried to upgrade the mirror I messed up.  I ended up with the following:

Disk	Size (MB)	Description	Device model	Virtual device	Pool
da0	1907730	Seagate Barracuda Green (AF)	ST2000DL003-9VT166	tank_mirror_0	tank
da1	1907730	Seagate Barracuda Green (AF)	ST2000DL003-9VT166
da2	2861589	Seagate Barracuda 7200.14 (AF)	ST3000DM001-1E6166	vault_mirror_1	vault
da3	2861589	Seagate Barracuda 7200.14 (AF)	ST3000DM001-1E6166
da4	3815448	Seagate NAS HD	ST4000VN000-1H4168	vault_disk_2
da5	3815448	WD Red	WDC WD40EFRX-68WT0N0	VeryTemp	VeryTemp

da4 ended up being added in serial not in parallel fashion.  I then added da5 and copied the content of the pool vault to it.  I am about to add another drive in parallel with da5 (thus making VeryTemp a mirror) and remove da2, da3 and da4.

Mirror Upgrade

My NAS is configured with two mirrors for file sharing (over SMB) with other Windows computers:

Disk	Size (MB)	Description	Device model	Virtual device	Pool	Dataset	Path	SMB Share
da0	1907730	Seagate Barracuda Green (AF)	ST2000DL003-9VT166	tank_mirror_0	tank	alex	/mnt/tank/alex/	alex
da1	1907730	Seagate Barracuda Green (AF)	ST2000DL003-9VT166			music	/mnt/tank/music/	music
da2	2861589	Seagate Barracuda 7200.14 (AF)	ST3000DM001-1E6166	vault_mirror_1	vault	alex
da3	2861589	Seagate Barracuda 7200.14 (AF)	ST3000DM001-1E6166			movies	/mnt/vault/movies	movies

I plan to purchase two 4TB drives to upgrade mirror vault.  Then after 30 or so days I will use these hard drives to upgrade mirror tank.
I did this successfully in the past.  This time I will document the procedure and will try to stay away from command line.

I powered down the system, installed new hard drive - there are plenty of empty positions available in the drive cages, powered the system up.
New drive da4 immediately appeared in Diagnostics\Information\Disks.
I go to Disk\Management,
da4 is not there.
I click Rescan Disks.
da4 appears.  I edit it to: set APM to 127,  activate SMART.
Apply changes.
I click Disk\Format, select da4 and specify ZFS.
Diagnostics\Information\Disks for da4 looks like this:

Device	Device model	Description	Size	Serial number	Rotation rate	Transfer rate	S.M.A.R.T.	Controller	Controller model	Temperature	Status
da4	ST4000VN000-1H4168	n/a	3815448MB	Z30150F6	5900 rpm	6.0 Gb/s	Available , Enabled	mps0	LSI SAS2008	35 °C	ONLINE

Time to add da4 to mirror vault.
This post outlines the steps involved in maintaining the mirror.  In a nutshell it recommends to take one disk offline and to add another thus replacing the first one.  I am a proponent of a different approach.  You add a 3rd disk to a mirror.  You leave it there for a while.  In the meantime not only old files are copied to the new disk.  Also all I/O operations are duplicated to 3rd disk and early failure might be detected.  If disk still works after 30 days, you can remove one of the older disks.  Add anew larger capacity disk.  Repeat.
The above approach relies on command

zpool add <existing pool> <device>

Unfortunately I found no way to issue it through GUI, thus the need to use command line:

Edit: nest post will be about a proper way to upgrade the mirror.