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Linux IDE Disk Servers. Andrew Sansum 8 March 2000. Acknowledgements. Big thanks to Fabien Collin (CERN). Things to look for in a disk server. Reliability(H/W + S/W) Crash Recovery (Journeled Filesystem) Performance Manageability (eg for Compaq/True64)
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Linux IDE Disk Servers Andrew Sansum 8 March 2000
Acknowledgements • Big thanks to Fabien Collin (CERN)
Things to look for in a disk server • Reliability(H/W + S/W) • Crash Recovery (Journeled Filesystem) • Performance • Manageability (eg for Compaq/True64) • Filesystems (ADVFS is very friendly) • Disk tools (SCU is good low level utility) • Monitoring (SCSI diagnostics) • Cost - MAJOR MOTIVATING FACTOR
What I’m not going to tell you SCSI Is better than IDE Linux is better than Solaris PC hardware is better than DEC HW RAID is better than S/W raid What I will tell you New test setup meets many of our requirements Will move server into production shortly What I won’t/will tell you
Benchmark • Benchmark was principally done using Bonnie: • Sequential Benchmark • Character by Character read/write • 4K Block read/write • Multiple threads tested by running multiple instances - some problems. • Results consistent with st.d (another benchmark)
Existing Systems • To put the new service into context - have a quick look at existing systems. • DEC 3000 Model 400 + Seagate Barracuda 4 on Normal Single ended SCSI • DEC AlphaServer 1000+7200rpm Fujitsu on Ultra Wide SCSI • DEC 1000+Sweet Valley H/W RAID • Sun Ultra 10 + Sun A1000 H/W RAID
IDE Disk Server Configuration • Dual PIII 500MHz CPUs + 256MB Memory • Intel L440GX Server motherboard (onboard VGA/100Mb Network/SCSI) • Single internal SCSI System Disk • 4 Promise dual ATA66 controllers • ATA66 cables • 10 IBM 7200 rpm 35GB IDE drives (tested 20) • Chieftec Jumbo File Server Case. Dual redundant PSU - Disk Cooler Trays
Operating System • Redhat 6.1 • Kernel 2.2.13 • Recent IDE patch to increase number of controllers and specifically the Promise Controller • Software RAID patch
Problems/Considerations • None of the ones quoted by suppliers • Not enough IRQs • Cannot run than four IDE controllers • No more than 2 Promise cards • Power supply awkward (daisy chains) • IDE Cable length (1M) is beyond the standard. Initially had CRC checks before moving to ATA 66 cables.
Filesystem Configuration • SCSI • Six Drives on single onboard controller • IDE • 10 Drives on 5 Controllers Master/Slave • Software RAID (0 or 5) with 32K chunk • Ext2 Filesystem with 4K block (and span 8)
NFS Performance • Not fully load tested - only 100Mbit connection • NFS to single RH 6.1 client gives: • 8MB/Second write • 7.3MB/S read • Possibility to install Gbit NIC on spare 66MHZ slot (second bus).
Reliability Crash Recovery Performance Manageability Cost Solid under test No JFS yet(raiserfs?) Excellent Worse than some Good Is the server suitable
COST • Difficult to get PC Builders to make it. Eventually used a specialist company (Workstations UK). - 11K for 720GB (inc VAT) • DIY is a better option • Cost of Drives - < 5K pounds • Total System - 7.5K for 720GB • Next system would be 20*IBM 72GB drive (1.5TB)
Conclusions • IDE drives give excellent performance • With fast CPUs, Software RAID gives excellent performance. • 20 drive PC can be built - although a few H/W concerns (cables mainly). • Some missing functionality with Linux (JFS, drive health monitoring). • 1.5TB server achievable any day now. • Server meets some (but not all) needs