Slow Sequential Read on RAID 1 ??? Why?

Im running I have a Intel 2500K Process and a 3TB RAID 1 on a 2 x SATA 3Gb/s Port on a Intel® Rapid Storage Technology RAID ARRAY. Im using the 3TB RAID 1 ARRAY for storage and im using a Crucial M4 128GB drive for my primary boot drive. My M4 drive operates normal. However on my RAID 1 ARRAY Ive noticed my Sequential Read speeds are slow, or at least they seem slow to me because im not sure if it is normal but my Sequential Read is around 75MB/s and the Sequential Write is around 140 MB/s which seems normal for the write. Is that Read supposed to be that slow on a RAID 1? If not why is it that my READ speed is so slow?? I've attached my CrystalDiskMark log below. My 3TB RAID 1 array are using a Seagate ST3000DM001 and a Seagate ST33000651AS


-----------------------------------------------------------------------
CrystalDiskMark 3.0.1 x64 (C) 2007-2010 hiyohiyo
Crystal Dew World : http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 73.481 MB/s
Sequential Write : 140.259 MB/s
Random Read 512KB : 49.253 MB/s
Random Write 512KB : 89.153 MB/s
Random Read 4KB (QD=1) : 0.728 MB/s [ 177.7 IOPS]
Random Write 4KB (QD=1) : 1.233 MB/s [ 300.9 IOPS]
Random Read 4KB (QD=32) : 3.247 MB/s [ 792.7 IOPS]
Random Write 4KB (QD=32) : 1.271 MB/s [ 310.3 IOPS]

Test : 500 MB [E: 33.6% (938.8/2794.4 GB)] (x2)
Date : 2012/02/22 8:51:38
OS : Windows 7 Ultimate Edition SP1 [6.1 Build 7601] (x64)
2 answers Last reply
More about slow sequential read raid
  1. Harddisks read slower than they write. If you set up RAID 1 thinking to increase you read/write speeds it won't work, you need RAID 0 instead. Those speeds look alright to me but I don't know what those drives are supposed to run at. Keep in mind you read/write speeds will be limited to your slowest drive in RAID 1.
  2. Im not trying to increase speed, im just trying to maintain decent stock speeds, according to these two articles (linked below) both drives seem to sequential read at almost the same speed as the SEQ WRITE, my READ speed is almost HALF of my WRITE, obviously something is wrong. I just down know whats wrong. Anyone know?

    http://www.storagereview.com/seagate_barracuda_3tb_review_1tb_platters_st3000dm001

    http://www.storagereview.com/seagate_3tb_barracuda_xt_review_st33000651as
Ask a new question

Read More

NAS / RAID Rapid Storage Storage