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Very Slow SSD


edan
18-08-2014, 13:10
Quote Originally Posted by Kode
I'm not sure what configuration 3 x drives is in, RAID 5? If so you may be able to get faster than single drive performance. Don't forget that is write performance so in real world usage where most of your actions are likely to be read operations the speed should be faster than a HDD especially as the IOPS should be much higher
Yes setup it as raid 5 for the data. Lot of VPS users like to see high I/O speed even they don't use it that much

Kode
18-08-2014, 09:05
I'm not sure what configuration 3 x drives is in, RAID 5? If so you may be able to get faster than single drive performance. Don't forget that is write performance so in real world usage where most of your actions are likely to be read operations the speed should be faster than a HDD especially as the IOPS should be much higher

edan
18-08-2014, 08:35
Quote Originally Posted by Criot
You'll find that with the S3500 SSDs the more storage capacity you have, the better performance you're going to get out of them.

Comparison table here: http://www.intel.com/content/www/us/...00-series.html
Hmm, I got better speed when using hdparm.

-T
Perform timings of cache reads for benchmark and comparison purposes. For meaningful results, this operation should be repeated 2-3 times on an otherwise inactive system (no other active processes) with at least a couple of megabytes of free memory. This displays the speed of reading directly from the Linux buffer cache without disk access. This measurement is essentially an indication of the throughput of the processor, cache, and memory of the system under test. If the -t flag is also specified, then a correction factor based on the outcome of -T will be incorporated into the result reported for the -t operation.
-t
Perform timings of device reads for benchmark and comparison purposes. For meaningful results, this operation should be repeated 2-3 times on an otherwise inactive system (no other active processes) with at least a couple of megabytes of free memory. This displays the speed of reading through the buffer cache to the disk without any prior caching of data. This measurement is an indication of how fast the drive can sustain sequential data reads under Linux, without any filesystem overhead. To ensure accurate measurments, the buffer cache is flushed during the processing of -t using the BLKFLSBUF ioctl. If the -T flag is also specified, then a correction factor based on the outcome of -T will be incorporated into the result reported for the -t operation.

Criot
18-08-2014, 02:12
You'll find that with the S3500 SSDs the more storage capacity you have, the better performance you're going to get out of them.

Comparison table here: http://www.intel.com/content/www/us/...00-series.html

edan
18-08-2014, 02:06
Quote Originally Posted by Kode
http://ark.intel.com/products/75678/...-6Gbs-20nm-MLC

Sequential write is rated at 135 MB/s
So this is the max? da*mn, I though I have a really bad configurations but its not.

Code:
root@bhs1 ~]# hdparm -tT /dev/sdc

/dev/sdc:
 Timing cached reads:   25506 MB in  2.00 seconds = 12773.00 MB/sec
 Timing buffered disk reads: 748 MB in  3.01 seconds = 248.70 MB/sec

[root@bhs1 ~]# hdparm -tT /dev/sdb

/dev/sdb:
 Timing cached reads:   25712 MB in  2.00 seconds = 12876.75 MB/sec
 Timing buffered disk reads: 748 MB in  3.00 seconds = 249.29 MB/sec

[root@bhs1 ~]# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   25576 MB in  2.00 seconds = 12808.63 MB/sec
 Timing buffered disk reads: 748 MB in  3.01 seconds = 248.82 MB/sec

Kode
18-08-2014, 00:37
http://ark.intel.com/products/75678/...-6Gbs-20nm-MLC

Sequential write is rated at 135 MB/s

edan
17-08-2014, 21:29
Hi,

Just rent E3-SSD-3 with 3x120GB SSD, but I noticed if the speed is very slow, even much slower compared to SYS-IP-1 (2x2TB SATA).

Code:
[root@bhs1 ~]# dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync; rm -rf test
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 8.13314 s, 132 MB/s
My SATA can reach 160 MB/s.

I use this configuration for the S/W RAID

Code:
[root@bhs1 ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [raid1]
md1 : active raid1 sda1[0] sdc1[2] sdb1[1]
      15727552 blocks [3/3] [UUU]

md2 : active raid5 sdb2[1] sdc2[2] sda2[0]
      201925632 blocks level 5, 512k chunk, algorithm 2 [3/3] [UUU]

unused devices: 
So when partitioning using the manager I set it like this:
Code:
boot -> raid 1
swap -> raid 1
home -> raid 5
Weird if SSD can only run this much.