When configuring storage for database servers, the write cache behavior of SATA disks becomes critical. Many database administrators disable disk write caching entirely due to concerns about data integrity - specifically the risk of disks acknowledging writes before they're actually persisted to physical media.

We want drives that either:

• Don't acknowledge writes until they're physically written to disk
• Properly implement the SATA FLUSH CACHE command (0xEA)
• Provide accurate reporting of cache status through SMART data

Based on extensive testing in production environments, these drives consistently handle write caching properly:

// Sample code to verify cache behavior (Linux)
#include 
#include 
#include 

int check_write_cache(int fd) {
    struct hd_driveid id;
    if (ioctl(fd, HDIO_GET_IDENTITY, &id)) {
        perror("HDIO_GET_IDENTITY");
        return -1;
    }
    return (id.command_set_2 & 0x04) ? 1 : 0;
}

Enterprise-class SATA drives generally implement more reliable write caching:

For MySQL/MariaDB setups where you've verified reliable cache behavior:

# my.cnf optimizations for cached drives
[mysqld]
innodb_flush_method = O_DIRECT
innodb_doublewrite = 1
innodb_io_capacity = 2000
innodb_io_capacity_max = 4000

Implement these checks in your monitoring system:

#!/bin/bash
# Check for cache flushes
cache_flushes=$(smartctl -a /dev/sda | grep "CacheFlush_Count" | awk '{print $NF}')
if [ $cache_flushes -eq 0 ]; then
    echo "WARNING: No cache flushes detected"
    exit 1
fi

When configuring database servers, one critical consideration is whether to enable disk write caching. Many DBAs disable this feature due to concerns about data integrity, but this often comes at significant performance costs. The core issue lies in how different disk models handle write acknowledgments.

Disks with proper write caching implementations will either:

• Delay write acknowledgment until data is physically written to platters
• Accurately report cache status when flushed (via proper SATA command handling)

Based on empirical testing and vendor documentation, these models demonstrate reliable write caching behavior:

# Sample disk verification command (Linux)
hdparm -I /dev/sdX | grep -A5 "Write cache"
# Look for:
#    * Write cache: enabled
#    * Write cache reordering: no
#    * Non-volatile cache: present (for models with capacitor-backed cache)

Testing methodology for write cache reliability:

#!/bin/bash
# Simple write test with verification
dd if=/dev/zero of=testfile bs=1M count=1000 conv=fdatasync
# Immediately pull power after completion
# Verify data integrity after reboot

For budget-conscious deployments:

• Western Digital Red Pro (with WDC's enterprise caching firmware)
• Seagate IronWolf Pro (PowerChoice enabled)
• Toshiba N300 (with specific firmware updates)

When using hardware RAID controllers:

# MegaCLI example for cache policy
/opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp -Direct -LALL -aALL
/opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp -Cached -LALL -aALL

Additional safeguards for critical data:

# XFS mount options example
UUID=xxxx-xxxx /data xfs defaults,noatime,nodiratime,logbsize=256k,logbufs=8 0 2

Key metrics to watch:

# iostat for write cache effectiveness
iostat -x 1
# Look for:
#    %util should be low during steady writes
#    await should be consistent