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Problem with CSSD-V30GB2A 30GB NOVA 2


kingneutron

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Hello; 1st thing I did after opening the box, was plug this drive into a Freebsd-64 system for some I/O testing. Real-world Write speed on the raw, unformatted SSD was about where Tom's HW said it would be - about 100MB/sec.

 

Read speed was atrocious - reading the 1st 1GB of the drive using DD took 81-82 Seconds, or ~12.7 MB/sec. :mad:

 

The tests that I ran are the same ones I use on spinning-disk drives, as such: (using bash shell)

 

# Write test: 3 runs

time (dd if=/dev/zero of=/dev/ada3 bs=1M count=1000;sync)

Run1: 0m10sec

Run2: 0m10.5sec

Run3: 0m9.97sec

 

# Read test: 2 runs

time (dd if=/ada3 bs=1M count=1000;sync)

Run1: 1m21sec

Run2: 1m22sec

 

---

 

At this point, I removed the drive and put it in a Windows 7--64 machine.

Formatted the drive as NTFS, Quick format, default settings.

 

I ran Invirtus Freespace on it (writes zeros till drive is full) and got ~87MB/sec consistently - which while not horrible, is still slower than what I would expect from a drive that is advertised as being capable of writing over 200MB/sec.

 

http://www.corsair.com/us/ssd/nova-series-ssd.html

 

This is hardly what I would call a "quantum leap" over my existing spinning disks. :evil:

 

Anyhow, then I copied a couple of directories that were ~8GB to the drive, using Win7's Explorer, one at a time - the copy (Detailed view) actually *stopped* both times for almost a minute, and then resumed at ~25-30MB/sec.

 

Needless to say, I don't think I can use this (my first SSD drive) for the use I was intending - as an unformatted cache drive for my ZFS raid. The existing 6x500GB RAIDZ2 *without* the SSD cache drive is capable of writing 1GB to ZFS using the above DD method in ~10 seconds, and reading ~7.8GB in 43-46 seconds. :D:

 

Update: the 3rd folder copy of ~7.83GB on Win7--64 did -not- stop entirely; the copy started out ~127MB/sec, which is consistent with the amount of cache on the drive - and then started slowing down significantly as the copy progressed, with the slowest speed going all the way down to 48.5MB/sec.

 

My question is, ATTO benchmarked** the drive as being "normal" - but real-world data I/O is much slower than expected.

 

** Benchmark settings:

 

Transfer size: 512 - 8192 KB

Total length: 1GB

v/ Force Write access

v/ Direct I/O

v/ Overlapped I/O

Queue depth: 4

 

** Benchmark results:

 

512.0 - Write: 228447 / Read: 295548

1024 - W: 226474 / R: 261888

2048 - W: 225103 / R: 262528

4096 - W: 224632 / R: 261888

8192 - W: 224632 / R: 260616

 

---

 

Freebsd detected the drive as " Corsair Nova 2 SSD 5.02 " -- should I RMA the drive? I'm pretty disappointed with it so far. :confused:

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I am sorry but you will need to use Parted Magic and secure erase the drive, writing one's or zeros to the drive will degrade performance. Then quick format in Windows 7 and run ATTO. And CENTOS 6.X has a benchmark that is fairly accurate and detects and works well with SSD's
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Thanks for your help; I got the SSD erased/reset and added it as a ZIL log to my ZFS RAIDZ2. It's running fine now :D:

 

*** FYI: To save someone else from the same mistake I made: When adding an SSD to an existing RAIDZ2, **DON'T** use the -f flag to force it on while using the wrong syntax! I had to backup the pool and recreate it in order to drop the SSD and re-integrate it properly.

 

BAD:

 

pool: tank1

state: ONLINE

scan: scrub repaired 0 in 2h1m with 0 errors on Tue Jul 31 23:22:25 2012

config:

 

NAME STATE READ WRITE CKSUM

- tank1 ONLINE 0 0 0

-- raidz2-0 ONLINE 0 0 0

--- label/zdisk1 ONLINE 0 0 0

--- label/zdisk2 ONLINE 0 0 0

--- label/zdisk3 ONLINE 0 0 0

--- label/zdisk4 ONLINE 0 0 0

--- label/zdisk5 ONLINE 0 0 0

--- label/zdisk6 ONLINE 0 0 0

-- label/ZILtank1 ONLINE 0 0 0 (!!!!!!)

 

--

 

zpool destroy tank1

 

zpool create tank1 raidz2 label/zdisk{1..6}

 

--

 

GOOD:

 

zpool add tank1 log label/ZILtank1

 

pool: tank1

state: ONLINE

scan: none requested

config:

 

NAME STATE READ WRITE CKSUM

- tank1 ONLINE 0 0 0

-- raidz2-0 ONLINE 0 0 0

--- label/zdisk1 ONLINE 0 0 0

--- label/zdisk2 ONLINE 0 0 0

--- label/zdisk3 ONLINE 0 0 0

--- label/zdisk4 ONLINE 0 0 0

--- label/zdisk5 ONLINE 0 0 0

--- label/zdisk6 ONLINE 0 0 0

-- logs

--- label/ZILtank1 ONLINE 0 0 0

 

errors: No known data errors

 

---

 

zfs set atime=off tank1

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