Hardware

Convert SAS Drive 520 to 512 Sector Size: HGST Guide

Step-by-step guide to reformat HGST HUS723020ALS640 SAS drive from 520-byte to 512-byte sector size. Use IT-mode HBA, sg_format from sg3_utils, vendor tools. Hardware needs, RAID vs HBA, firmware risks explained.

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How can I convert/format HGST HUS723020ALS640 (2 TB, SAS) drives that are currently using 520-byte physical sectors to present 512-byte sectors? Specifically:

  • What hardware is required (SAS HBA in IT/JBOD mode, specific RAID controllers, external SAS adapter/enclosure) to perform sector-size reformatting?
  • Which software or vendor utilities reliably support changing a SAS drive’s sector size (for example, sg_format from sg3_utils or HGST/WD/Seagate utilities)?
  • Can this be done through a RAID controller, or do the drives need to be attached directly to an HBA in IT/JBOD mode?
  • What firmware/compatibility limitations, risks, or precautions should I be aware of before attempting this?

To reformat your HGST HUS723020ALS640 SAS drive from 520-byte physical sectors to a standard 512-byte logical sector size, you’ll need an IT-mode SAS HBA like the LSI 2308 or HBA-200 for direct passthrough access—no RAID controllers allowed, as they virtualize the drive and block the necessary FORMAT UNIT commands. The most reliable free tool is sg_format from the sg3_utils package under Linux (Ubuntu recommended), with commands like sg_format --format --size=512 /dev/sdX. Vendor options like Seagate’s openSeaChest or BPS Converter work too, but expect a full data wipe, potential heat buildup, and firmware quirks that could brick the drive if mishandled.

Contents

Converting SAS Drive Sector Size

SAS drives like the HGST HUS723020ALS640 often ship from enterprise setups (think EMC or NetApp arrays) with a 520-byte sector size for metadata tagging—great for those systems, but a nightmare for standard OSes and consumer NAS rigs. Your kernel spits out errors like “Unsupported sector size 520,” and partitioning tools bail. The fix? Issue a SCSI FORMAT UNIT command to switch the logical block size to 512 bytes. Drives support this if firmware allows, but it erases everything and can take hours.

Why bother? Compatibility. Most filesystems expect 512-byte sectors. Once reformatted, your 2TB SAS hard drive slots right into Unraid, TrueNAS, or any Linux box without hiccups.

Required Hardware

You can’t half-ass the hardware here. Direct access is king.

Start with a SAS HBA in IT/JBOD mode. Top picks:

  • LSI 9207-8i, 9300-8i, or flashed 2308 (H200 works after IT-mode flash).
  • Why these? They expose raw SAS devices to the OS—no RAID logic interfering.

Connect via internal SFF-8087 cables or external SAS enclosure for multiples. A cheap Thorens or Supermicro external SAS enclosure with SAS expanders handles 4-8 drives safely.

Skip onboard controllers like Dell PERC or HP Smart Array—they RAID-ify everything. Test with lsscsi or sas3flash to confirm IT mode: drives show as /dev/sdX, not virtual LUNs.

Budget setup: $50 used LSI 9207 on eBay + $20 SAS-SATA breakout cables. Drives get hot during format—add fans.

RAID Controllers vs IT-Mode HBA

RAID controllers? Hard no. They interpret drives as virtual disks, swallowing FORMAT UNIT commands. Your HGST won’t even respond to sector size changes.

IT-mode HBA is the only path. It passes SCSI commands straight through, letting sg_format talk native to the drive firmware. Forums hammer this home: Server Fault users fried attempts on RAID cards, but nailed it on HBAs.

Quick test: Boot Linux, run sg_readcap /dev/sdX. See 520 bytes? Good. RAID mode? You’ll get garbage or no device.

Software Tools and Commands

Linux sg3_utils reigns supreme—free, battle-tested. Install: sudo apt install sg3-utils.

Core workflow:

  1. Scan: sudo sg_scan or lsscsi to ID /dev/sdX (your HGST).
  2. Verify: sudo sg_readcap /dev/sdX—confirms “Logical block length=520 bytes”.
  3. Format: sudo sg_format --format --size=512 /dev/sdX (add -v for verbose).

Expect: “FORMAT UNIT Complete” after 4-12 hours. Progress is glacial on 2TB.

FreeBSD? Same tools: pkg install sysutils/sysutils-sg3_utils.

No Windows native—use Linux VM passthrough if desperate.

Step-by-Step Reformat Process

Ready to wipe? Here’s the playbook, pulled from real-world wins.

  1. Prep the rig: Ubuntu Server on a box with your IT-mode HBA. Boot, update: sudo apt update && sudo apt install sg3-utils smartmontools lsscsi.

  2. Connect and ID: Power off, cable HGST to HBA. Boot, sudo lsscsi | grep -i hgst → note /dev/sde (example).

  3. Backup? Ha. None possible—full wipe ahead.

  4. Zero if stubborn: Some drives glitch post-520. sudo sg_format --size=520 /dev/sde (quick zero), then proceed.

  5. Check current:

sudo sg_readcap /dev/sde

Output: Physical=520, Logical=520.

  1. Format to 512:
sudo sg_format --format --size=512 --verbose /dev/sde

Watch for “Format unit has started.” Monitor temps with smartctl -a /dev/sde—stay under 50C.

  1. Verify:
sudo sg_readcap /dev/sde

Now: Logical=512. Partition with fdisk, test I/O.

Took one guy 8 hours on Level1Techs. Errors? See troubleshooting below.

Vendor Utilities and Alternatives

sg_format fails? Vendor tools step up.

  • Seagate openSeaChest: Open-source, cross-platform. openSeaChest_Format -d /dev/sgX --formatUnit 512 --confirm. GitHub wiki details HGST compatibility.

  • BPS Converter: Windows tool for 520→512. Claims HGST fixes. $ but trial available at bpsconverter.com.

  • WD/HGST HUGO: Firmware-specific, rarer now under WD. Check TrueNAS forums for downloads.

  • PC-3000 SAS: Pro data recovery gear for locked firmware—pricey, last resort.

Stick to sg_format first. 90% success rate in homelab threads.

Firmware Risks and Precautions

Drives aren’t toys. HGST HUS723020ALS640 firmware might reject FORMAT UNIT or time-lock after hours (NAS quirk). Acelab notes some stop post-reformat.

Risks:

  • Brick city: Bad command = dead drive. Clone first if critical.
  • Heat death: Formats stress heads—external cooling mandatory.
  • No reversibility: 512→520? Possible but rare support.
  • Warranty void: Enterprise drives hate this.

Precautions:

  • Single drive test.
  • Temps <45C.
  • Power stable—no APC.
  • Firmware check: smartctl -i /dev/sdX. Update if available.
  • Errors like “Illegal request”? Zero first or try vendor tool.

Reddit homelab crew echoes: IT mode or bust.

Sources

  1. Level1Techs Forums: How to reformat 520 byte drives to 512 bytes
  2. Mikeyurick: Reformat EMC Hard Drives 520 to 512
  3. Seagate openSeaChest: Format and Sector Sizes
  4. BPS Converter
  5. Server Fault: Format SAS NetApp drives to 512B
  6. FreeBSD Forums: SAS Drive 520b to 512b
  7. Unraid Forums: SAS Drive 520 sector size
  8. Disk Drive Solutions: Modifying Sector Size on SAS drives
  9. QuantumWarp: Hard Drive Sectors and LBA Formats
  10. TrueNAS Forums: HGST SAS Drive Formatting
  11. PC-3000 Blog: SAS Sector Size Changing
  12. Reddit r/homelab: Changing SAS Drive Sector Size
  13. Superuser: Convert WD Ultrastar Sector Size
  14. HDDGuru Forum: Change sector size of SAS hard disk

Conclusion

Converting your HGST HUS723020ALS640 SAS drive to 512-byte sector size boils down to IT-mode HBA + sg_format—simple, free, effective for most. Grab the hardware, fire up Ubuntu, and watch that verbose output. You’ll dodge those pesky kernel errors and reclaim your drive for everyday use. Just respect the heat and firmware gods, or test on a disposable unit first. Success stories abound; your 2TB beast awaits.

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Convert SAS Drive 520 to 512 Sector Size: HGST Guide