# low SSD write speed

## Schmolch

I got a Supertalent 60GB SSD with claimed speeds of up to 120MB/s read and 80 MB/s write.

I did confirm those numbers with a Windows benchmark tool (atto).

Using bonnie++ however i only get 30MB/s write and 100MB/s read.

When i use bonnie++ on my 5400rpm drive i get about 50MB/s read and write which seems ok.

Now, what is wrong here?

The SSD is fine since the numbers are good in Windows.

Bonnie++ also is fine since it reports good numbers for my 5400rpm drive.

But why is it reporting such low write-speeds with the SSD?

----------

## WackyDoo

When the device is mounted, type "mount".  Is the SSD mounted with the 'sync' option? See "man mount" for more info.

Generally drives are much slower with the sync option, since the cache is flushed after each write.  On the other hand, if you remove the device without unmounting, sync will improve your chances of not having file corruption.

----------

## poly_poly-man

First of all, is this on an IDE or a SCSI/SATA interface (basically, is it /dev/hd* or /dev/sd*?)

If it's on IDE, try setting DMA on using hdparm's -d option.

In either case, you can test read times on the drive with hdparm's -t option (-T results are highly skewed).

----------

## Schmolch

The SSD is not mounted with the sync option:

```
/dev/sda6 on / type ext3 (rw,noatime)

proc on /proc type proc (rw,nosuid,nodev,noexec)

sysfs on /sys type sysfs (rw,nosuid,nodev,noexec)

udev on /dev type tmpfs (rw,nosuid,size=10240k,mode=755)

devpts on /dev/pts type devpts (rw,nosuid,noexec,gid=5,mode=620)

shm on /dev/shm type tmpfs (rw,noexec,nosuid,nodev)

usbfs on /proc/bus/usb type usbfs (rw,noexec,nosuid,devmode=0664,devgid=85)

/dev/sda5 on /media/Intrepid type ext3 (rw,nosuid,nodev,uhelper=hal)

/dev/sda7 on /media/empty type ext3 (rw,nosuid,nodev,uhelper=hal)

/dev/sda8 on /media/Storage type ext3 (rw,nosuid,nodev,uhelper=hal)

/dev/sda2 on /media/Hardy type ext3 (rw,nosuid,nodev,uhelper=hal)

```

It is a SATA2 SSD:

```

Commands/features:

   Enabled   Supported:

      *   SMART feature set

      *   Power Management feature set

          Write cache

          Look-ahead

      *   Mandatory FLUSH_CACHE

      *   SATA-I signaling speed (1.5Gb/s)

      *   SATA-II signaling speed (3.0Gb/s)

      *   Host-initiated interface power management

      *   Phy event counters

Checksum: correct

```

connected to:

```

00:1f.2 IDE interface: Intel Corporation 82801GBM/GHM (ICH7 Family) SATA IDE Controller (rev 02)

```

The hdparm -tT results are alright:

```

hdparm -tT /dev/sda

/dev/sda:

 Timing cached reads:   2422 MB in  2.00 seconds = 1212.20 MB/sec

 Timing buffered disk reads:  266 MB in  3.00 seconds =  88.53 MB/sec

```

bonnie++ reports read-speeds up to 100MB/s but as i said the write-speeds are very disappointing with only 30MB/s max.

How could i copy a large file from RAM to SSD for a simple write-speed benchmark?

----------

## poly_poly-man

hmm... you would rteally have to bypass the filesystem in order to get an accurate measure...

If you don't mind getting rid of all the data on the drive, you can use dd (from a livecd or whatever) to write to it.. something like

dd if=/dev/zero of=/dev/sda bs=1G count=1

bs should fit snugly in your ram... adjust to suit. Compare to value with of=/dev/null.

----------

## Schmolch

Im not looking for precision here.

I get at most 30MB/s in Linux and up to 80MB/s in Windows.

The mount-options and filesystem overhead do not explain why i get less than 40% of the write-performance with Linux.

----------

## Schmolch

I made a 1GB Ramdisk and filled it with 900MB of files.

I copied from Ramdisk to SSD and vice versa several times and the results are:

~77MB/s read

~38MB/s write

Write is still too slow.

I dont know what bonnie++ exactly does but with this simply benchmark i am now more convinced that something is wrong.

----------

## albright

I seem to remember something about vista having some

special features to improve ssd function ... or maybe

MS just has access to some extra information for driver

writing. And just to be sure, you have verified you actually

get the fast write speeds in windows (that is, you are not

just relying on the benchmarker)?

----------

## Schmolch

I heard the opposite, that SSDs run horrible with vista.

I used a very old windows XP (CD from 5+ years ago, no updates) though and only ran the benchmarker.

----------

## Schmolch

Here is a screenshot of the Windows-Benchmark:

[img]http://www.abload.de/thumb/atto50q.jpg[/img]

As you can see it goes above 70MB/s write-speed very easily.

When i copied large files from my ramdisk to the SSD in Linux i should have reached the highest possible speeds but all i got was 38MB/s which is only half of what i get in windows.

----------

