--- On Fri, 5/6/11, Paul B. <red [ dot ] line [ at ] rogers [ dot ] com> wrote:
> Roland,
> great results, but I'd like to request one clarification:
> did you constrain the hdd benchmark with the same ramdisk
> size as the
> SSD, or did you mess around with the ramdisk size only
> after running the
> comparison test?
Having checked my notes in more detail, I find the answer is neither,
I got the information from the internet before purchasing a drive.
However, as I mentioned in my previous post, it's noticably faster.
My systems with non-SSD disks sometimes have me wondering why they
seem slow until I remember I'm using a spinning disk.
The big gain is on seek time and latency.
I purchased the Crucial RealSSD C300 64GB mainly because of
the price (this was a test) and it had enough storage for me.
Data from my original WD Scorpio Black 320GB is available via a small
USB external HDD Enclosure (was $14 now $11 ).
I spent a while reading about SSDs.
1) Will they work with Linux?
2) What's the price range?
3) Although I'm mainly interested in building a quiet computer,
how will the speed compare with my existing disk since some
versions of the technology have very slow write speeds.
Here are my notes:
I've left out the price information to save space and since prices
have reduced significantly.
10/11/04
- Excellent description of SSD write life expectancy and operations.
http://www.anandtech.com/show/2829
The SSD Relapse: Understanding and Choosing the Best SSD
by Anand Lal Shimpi on 8/30/2009 12:00:00 AM
- Intel drives are the only ones that perform well.
- The controller is important.
- Nand flash has to be written 4KB at a time.
- Nand flash has to be erased 512KB at a time.
- A flash memory cell starts to fail after 10,000 writes.
Therefore, s/w must know how to block the writes and not
keep re-writing the same cell.
- Author finds (in Aug 2009) best drives are:
Intel X25-M
OCZ Vertex (based on Indilinx controller)
- Even the slow SSDs are fast with low power consumption.
http://torvalds-family.blogspot.com/2009/03/ssd-followup.html
Linus' blog - Wednesday, March 18, 2009
http://ssd-reviews.com/
SSD comparison database
10/11/05
- finished reading very good article
http://www.anandtech.com/show/2829
The SSD Relapse: Understanding and Choosing the Best SSD
Note: Newer data. Crucial C300 256GB is fast.
http://www.tweaktown.com/reviews/3118/crucial_realssd_c300_256gb_sata_6gbps_solid_state_disk/index11.html
Crucial RealSSD C300 256GB SATA 6Gbps Solid State Disk - Feb 3, 2010
shopRBC has:
Crucial RealSSD C300 64GB 2.5" SATA 6GBs Solid State Drive - $147.00
Intel X25V 40GB 2.5" SATA Solid State Disk - $139.00
X25-V MLC Solid State Drive
- Linux tweaks.
Read this if buying an SSD.
http://tombuntu.com/index.php/2008/09/04/four-tweaks-for-using-linux-with-solid-state-drives/
Four Tweaks for Using Linux with Solid State Drives - Sep 2008
- Mount ext3 volumes with relatime instead of noatime.
- Use ramdisk.
/etc/fstab
tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0
- Put Firefox cache in ram.
Open about:config in Firefox. Right click in an open
area and create a new string value called
browser.cache.disk.parent_directory. Set the value to /tmp.
- Change IO scheduler from
% cat /sys/block/sda/queue/scheduler (rjrl5 CentOS 5.3)
noop anticipatory deadline [cfq]
to
% echo deadline > /sys/block/sda/queue/scheduler
There are more details. Read the article.
Also read the user responses.
- MadMike says relatime is now standard with Ubuntu.
- Moving /var/log to tmpfs is also interesting.
- June 25, 2010 entry says:
Solid State disks now run straight out of the box for Linux.
http://www.linux-mag.com/id/7345
NILFS: A File System to Make SSDs Scream - Jun 2009
NILFS2 (New Implementation of a Log-Structured File System
Version 2) is a very promising new log-structured file
system that has continuous snapshots and versioning of the
entire file system.
... good performance on SSD drives.
10/11/23
- speed comparison between SSD and disk drives.
http://www.bit-tech.net/hardware/storage/2010/07/21/crucial-realssd-c300-64gb-ssd-review/4
Crucial RealSSD C300 64GB 2.5" SATA 6GBs Solid State Drive
ATTO Disk Benchmark
1,024KB Compressable Sequential Read Speed 360 MB/s
1,024KB Compressable Sequential Write Speed 80 MB/s
http://www.bit-tech.net/hardware/storage/2009/10/02/western-digital-2tb-caviar-black-review/3
Western Digital 2TB Caviar Black
HD Tach
Average Read 117 MB/s
Average Write 72 MB/s
Western Digital 2TB Caviar Green
Average Read 79 MB/s
Average Write 53 MB/s
http://www.legitreviews.com/article/955/2/
WD Scorpio Black 320GB 7200RPM 16MB 2.5" SATA Hard Drive
Average Read 71 MB/s
Average Write 66 MB/s
10/12/04
- summary: Crucial RealSSD is 5 times faster on read and 20% faster
on write than WD Scorpio Black 320GB.
10/12/05
http://www.zdnet.com/blog/perlow/geek-sheet-a-tweakers-guide-to-solid-state-drives-ssds-and-linux/9190
Geek Sheet: A Tweaker's Guide to Solid State Drives (SSDs) and Linux
- Jason Perlow Nov 18, 2010
Use the "noop" simple I/O scheduler.
- add block/sda/queue/scheduler = noop to your /etc/sysfs.conf
(requires the sysutils package) or elevator=noop to the kernel
boot parameters in your /etc/default/grub file
Change the file system mount options on SSDs to "noatime" and
mount your /tmp in RAM.
UUID=aaf49668-2624-4238-a486-baf341361be6 / ext4
noatime,discard,data=ordered,errors=remount-ro 0 1
Roland writes: (on May 5, 2011)
| I used "hdparm -t /dev/sda" on both drives for the read speed test.
| Offhand, I don't recall what I used to test writes.
I was in a hurry when I posted this.
Looking at my notes I find
- speed tests described in article above
Four Tweaks for Using Linux with Solid State Drives - Sep 2008
Rrjrl5 % hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 332 MB in 3.00 seconds = 110.56 MB/sec
Rrjrlap3% hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 666 MB in 3.00 seconds = 221.90 MB/sec
Machines
Rrjrl5 - Dell Optiplex GX620 Intel Pentium D 3.0 GHz (dual core)
- disk is Western Digital Caviar Black 500G
Rrjrlap3 - ThinkPad T500 Intel Core2 Duo processor P8400 2.26GHz
- disk is Crucial RealSSD
http://www.thegeekstuff.com/2008/11/overview-of-ramfs-and-tmpfs-on-linux/
Overview of RAMFS and TMPFS on Linux - Ramesh Natarajan Nov 6, 2008
The notes in the "Tweaks" article below don't show how to set the
ramdisk size.
Running the test on Rrjrlap3 again a few times, I get:
Rrjrlap3% hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 634 MB in 3.01 seconds = 210.77 MB/sec
Timing buffered disk reads: 656 MB in 3.00 seconds = 218.59 MB/sec
Timing buffered disk reads: 634 MB in 3.00 seconds = 211.04 MB/sec
Timing buffered disk reads: 634 MB in 3.00 seconds = 211.22 MB/sec
Conclusions:
- Running "hdparm -t /dev/sda" isn't a sufficient test to justify the
purchase of an SSD.
BTW: The one Robert Day is considering is a "hybrid SSD".
I don't know anything about that or how it differs.
- Reading internet articles can give some interesting background but
the speed tests are usually done on Microsoft operating systems.
- I think the main improvement with SSDs are reduced latency, less
noise and less power consumption.
Note that since Linux usually writes data as a background job, write
speeds often aren't noticed.
Hopefully, the pointers above will be of interest to someone
considering an SSD.
roland