I'm prepared to buy a SSD for testing. This will be my first experience using SSD.
CPU - AMD 8-Core FX-8150 3.6GHz/16M
Mobo - ASUS M5A97 R2.0 AMD 970,DDR3,USB3.0,SATA3 6Gb/s,ATX M/B
RAM - Corsair Vengeance CMZ32GX3M4X1600C10 DDR3 1600MHz 32GB Kit (4x8GB)
The SSD will be partitioned into 2 partitions. This will be a dualboot SSD, one partition running Ubuntu 12.04 desktop, 64bit for installing OpenStack and another partition running Fedora 17 desktop, 64 bit for installing oVirt.
The size of SSD expected to be 200G~256G, SATA 3 6Gb/s.
Please shed me some light on selecting the SSD. I have no preset budget. However I don't expect to get an expensive SSD for testing.
I normally just go for the speed as every SSD has a specification on how fast it can read and write. At the earlier stage I think there were more variations but it seems to have settled down.
I have only tried two types so far. One is an early Adata 128Gb Sata II capable of read up to 230MB/s and write at 170MB/s, bought probably 2.5 years ago. It was just another hard disk to me. ALthough it was faster than a normal hard disk I didn't got much of it and so it was used much at all.
About a month ago I was amazed by the newer Sata SSD spec and the price drop so I bought 4 Corsir Force GT 240GB Sata III which claims to be able to read up to 555MB/s and write up to 525MB/s. Two were for my rig and another two later for the wife's PC after seeing its performance in a Raid0 combination.
I used the command "hdparm -tT/dev/sda" etc to check the performance.
With a standard Sata III 3TB hard disk the buffered read was 187 MB/s.
My older Adata Sata II SSD clocked up 250 MB/s
A single Corsir Sata III SSD managed 450 to 460 MB/s
The real test to me is see how it work in practice as I put two together to form a Raid0 set. I was surprised by the about 15 seconds boot up time for each of Windiws 7, Windows 8 and Ubuntu. In a Raid0 set the hdparm reported 666MB/s which is faster than the claimed 555MD/s but not double, as in a Raid0 each SSD holds 50% of the data so theoretically the time to load a set of data should be halved but there should always be some overheads. In Windows the HDtune reported over 1000MB/s speed for the Raid0 set.
What it amazed me in the end was when I tried to clone the Raid0 set, as I got 4 SSD. To duplicate the 480Gb, with 3 operating systems inside, it took less than 17 minutes at a speed of 474MB/s. All these year whenever I cloned a hard disk I rarely get the speed passed 100Mb/s.
Thus I see SSD has a good future especially it has dropped the price significantly recently. About 256Gb size is good as it can hold at least two operating systems. Using them for Raid0 will definitely accelerate everything. When I bought my first SSD a few year ago it was already at the price of a USB jump drive on unit price basis. Although I have not used one SSD to its death yet but I do believe without moving parts it could last longer than a conventional hard disk. It does use a lot less power than the standard 2.5" hard disk (only about 1/3) and so easy to hoop up as an external USB hard disk.
It appears on the market many SSD are now capable of 500MB/s read and write speed.
In another thought I may get a 120G SSD first testing oVirt. Then buy another 120G SSD later testing OpenStack. I can't perform 2 tests simultaneously. Or after testing oVirt wipe it out to test OpenStack.
2 120G = 1 250G SSD in price, approx.
It'll save the problem on installing dualboot. If I need 240G capacity I just install RAID
Corsair Force Series 3 2.5" 120GB SATA 3 6Gb/s SSD
Kingston SSDNow V+ 200 Series 120GB 2.5" SATA 3 6Gb/s SSD
OCZ Agility 3 120GB, 2.5", SATA 3 6Gb/s
SanDisk Extreme 120GB 2.5" SATA3 6Gb/s
all are more less same price.
TEAM Xtreem S2 120GB 2.5" SATA 3 6Gb/s
is a little bid cheaper
Samsung 840 Series MZ-7TD120BW 120GB 2.5" SATA 3 6Gb/s
Intel 330 Series 120GB (Pretty Box) Maple Crest SSDSC2CT120A3K5 2.5" SATA 3 6Gb/s
are a little bid expensive.
Ah a further question would the speed of 250G SSD faster than that of 120G SSD?
I read a few write-ups which generally praised Samsung among the top. Corsir is also cosistently near the top.
As I did not have Samsung I could only offer the tests I did on Corsir Force GT.
Samsung spec seems to have a low speed for sequential read of 160Mb/s to 250Mb/s depending whether one buys the 830 or 840 series.
Corsir Force GT only claims maximum sequential read/write speed of 555/525 MB/s for 120GB size and this figures for 240GB is 555/525MB/s (which is the one I have). Thus a Corsir Force GT 120GB SSD is marginally slower than the bigger capacity of 240GB. Other manufacturers also show the similar trend and units above 256GB apparently marginally slower too.
I did get 474MB/s in cloning RAID0 which to me is the acid test of sequentially reading 480GB and writing the 480GB data on another pair of SSD.
Spec wise the Corsir Force GT is significantly better and able to deleiver the rated speed in practice.
I had moved the content of a Linux partition, about 60Gb, in a single SSD when I needed to move Ubuntu and Mint around in different partitions (like from sda8 to sda6). It was so fast that I didn't bother recording the time. The above 474MB/s speed was using dd which read and write empty space. In moving I used tar which operates on the filing system and moves only data and does not waste time on the empty space.
I still believe the specification of the read/write speed to be the key factor. Afterall it is the speed one goes into SSD by paying the extra to get data storage.
I found the price of;
OCZ Agility 3 240GB, 2.5", SATA 3 6Gb/s (Solid State Drive, SSD) [AGT3-25SAT3-240G]
is quite interesting. It is about 70% more compared with;
OCZ Agility 3 120GB, 2.5", SATA 3 6Gb/s (Solid State Drive, SSD) [AGT3-25SAT3-120G]
The price of;
Corsair Force Series 3 2.5" 240GB SATA 3 6Gb/s SSD CSSD-F240GB3-BK
is double the price of;
Corsair Force Series 3 2.5" 120GB SATA 3 6Gb/s SSD CSSD-F120GB3A-BK
The price of 120G OCZ Agility 3 is same as 120G Corsair Force Series.
Do you know the performance of OCZ Agility 3 240GB. What are its read and write speeds? Thanks
I believe there is ample evidence to suggest a SSD needs to be aligned in order to maximize its performance.
The new fdisk program in a Linux kernel will start the SSD at 2048th Sector. It has been reported that the SSD should run at interval of 64 sectors instead of the standard 63 sectors normally found in a traditional SSD. Thus I cloned my SSD with a block size of 512x64 = 32768 byte in the dd command.
If the block size is omitted dd will default to 512 bytes per record this will definitely slow down the cloning process. By trial and error I found the cloning is best done with block size equal to a full track. Thus for a traditional hard disk I would use bs=32256 but for SSD it should be bs=32768.
Therefore the dd command could run faster with the bs parameter like
dd if=/sda/zero of=/dev/sda bs=32768
if every byte has to be zeroed first.
However I myself never zero a hard disk as I do not consider it necessary.
Operationally there is no need to bland a hard disk when a new partition is created or a new operating system installed.
When you delete the partition table of a hard disk its 64 bytes in the 512-byte MBR will be blanked but none of the internal data is touched. Thus deletion and creation of the partition table is a reversible process if you keep a record of it.
If you create a partition the OS will not be able to use it until you format it. Once formatted there is a filing index created at the front end resulting the old data nearly impossible to piece together. When you write on it the binary bits are then changed for the areas occupied by the file. Every operating system does it this way.
By blanking the disk you gain nothing except for security reason for passing a used disk to another user. Users who have sensitive data will also like to blank the disk, say for financial data, when change its use. Forensically people with special equipment can still recover the original data even after you have blanked the disk. I just never have had a need to blank a hard disk.