Question

1

Poor SSD RAID0 write performance, alignment on raid?

rated 0 times [ 1] [ 0] / answers: 1 / hits: 2058 / 3 Years ago, thu, may 27, 2021, 6:25:11

We have Samsung840Pro 512gb x2 connected to the motherboard's c600 6gbps SATA3.0 ports. The RAID partitions use 100% of each disk:

user@blockparty ~ $ sudo fdisk -lu /dev/sdb



Disk /dev/sdb: 512.1 GB, 512110190592 bytes

255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x000xxxxx



   Device Boot      Start         End      Blocks   Id  System

/dev/sdb1   *        2048  1000214527   500106240

(/dev/sda has the same layout)

When I write a file using dd:

user@blockparty ~ $ dd count=1k bs=8M if=/dev/zero of=benchfile.bin

1024+0 records in

1024+0 records out

8589934592 bytes (8.6 GB) copied, 32.341 s, 266 MB/s

That's 2gbps. Not exactly blowing my socks off here.

Is the problem our raid partition boundaries?

user@blockparty ~ $ sudo fdisk -lu /dev/md0



Disk /dev/md0: 1024.2 GB, 1024216530944 bytes

255 heads, 63 sectors/track, 124520 cylinders, total 2000422912 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 524288 bytes / 1048576 bytes

Disk identifier: 0x00013891



    Device Boot      Start         End      Blocks   Id  System

/dev/md0p1              63  1992220649   996110293+  83  Linux

Partition 1 does not start on physical sector boundary.

/dev/md0p2      1992220650  2000413799     4096575    5  Extended

Partition 2 does not start on physical sector boundary.

/dev/md0p5      1992220713  2000413799     4096543+  82  Linux swap / Solaris

Partition 5 does not start on physical sector boundary.

More info:

user@blockparty ~ $ sudo mdadm -D /dev/md0

/dev/md0:

        Version : 1.2

  Creation Time : Thu Apr 24 13:50:42 2014

     Raid Level : raid0

     Array Size : 1000211456 (953.88 GiB 1024.22 GB)

   Raid Devices : 2

  Total Devices : 2

    Persistence : Superblock is persistent



    Update Time : Thu Apr 24 13:50:42 2014

          State : clean 

 Active Devices : 2

Working Devices : 2

 Failed Devices : 0

  Spare Devices : 0



     Chunk Size : 512K



           Name : ubuntu-test:0

           UUID : a4e7ead8:fc9c14e1:70bad27e:78a91cbe

         Events : 0



    Number   Major   Minor   RaidDevice State

       0       8        1        0      active sync   /dev/sda1

       1       8       17        1      active sync   /dev/sdb1

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hamostic

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2 Years ago

answered 3 Years ago enincroscope · Accepted Answer

One of my software engineers said he had to update his BIOS to get decent SSD transfer speeds. Being a SuperMicro product, we had upgraded the IPMI we when received the board but apparently there is also BIOS firmware that's separate.

We upgraded the BIOS to the latest, and boom 1.2GB/s hdparm test. Moral up the story? Update your crap.

We need to upgrade the SSD firmware on the individual drives as well... save that for a night when we're feeling completely confident. Thank you for everyone that answered, you helped us get down the right path.