Messages in this thread | | | From | Witold Krecicki <> | Subject | raid0 slower than devices it is assembled of? | Date | Mon, 15 Dec 2003 14:34:54 +0100 |
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I've got / on linux-raid0 on 2.6.0-t11-cset-20031209_2107: <cite> /dev/md/1: Version : 00.90.01 Creation Time : Thu Sep 11 22:04:54 2003 Raid Level : raid0 Array Size : 232315776 (221.55 GiB 237.89 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 1 Persistence : Superblock is persistent
Update Time : Mon Dec 15 12:55:48 2003 State : clean, no-errors Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0
Chunk Size : 64K
Number Major Minor RaidDevice State 0 8 3 0 active sync /dev/sda3 1 8 19 1 active sync /dev/sdb3 UUID : b66633c2:ff11f60d:00119f8d:7bb9fc6c Events : 0.357 </cite> Disks are two ST3120026AS connected to sii3112a controller, driven by sata_sil 'patched' so no limit for block size is applied (it's not needed for it).
Those are results of hdparm -tT on drives: <cite> /dev/md/1: Timing buffer-cache reads: 128 MB in 0.40 seconds =323.28 MB/sec Timing buffered disk reads: 64 MB in 1.75 seconds = 36.47 MB/sec /dev/sda: Timing buffer-cache reads: 128 MB in 0.41 seconds =309.23 MB/sec Timing buffered disk reads: 64 MB in 1.46 seconds = 43.87 MB/sec /dev/sdb: Timing buffer-cache reads: 128 MB in 0.41 seconds =315.32 MB/sec Timing buffered disk reads: 64 MB in 1.23 seconds = 52.04 MB/sec </cite> What seems strange to me is that second drive is faster than first one (devices are symmetrical, sd[a,b]2 is swapspace (not mounted at time of test), sd[a,b]1 is /boot (raid1)). What is even stranger is that raid0 which should be faster than single drive, is pretty much slower- what's the reason of that? -- Witold Kręcicki (adasi) adasi [at] culm.net GPG key: 7AE20871 http://www.culm.net - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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